Gran Tierra Energy (GTE) 10-K 27 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-34018
Entity Registrant Name	GRAN TIERRA ENERGY INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-0479924
Entity Address, Address Line One	900, 520 - 3 Avenue SW
Entity Address, City or Town	Calgary,
Entity Address, State or Province	AB
Entity Address, Country	CA
Entity Address, Postal Zip Code	T2P 0R3
City Area Code	403
Local Phone Number	265-3221
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	GTE
Security Exchange Name	NYSEAMER
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 0.5
Entity Common Stock, Shares Outstanding		366,981,556
Documents Incorporated by Reference	The information required by Part III of this report, to the extent not set forth herein, is incorporated by reference from the registrant’s definitive proxy statement relating to the 2020 annual meeting of stockholders, which definitive proxy statement will be filed with the Securities and Exchange Commission within 120 days after December 31, 2019 .
Entity Central Index Key	0001273441
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
OIL AND NATURAL GAS SALES (NOTE 9)	$ 570,983	$ 613,431	$ 421,734
EXPENSES
Operating	142,086	111,272	87,855
Workover	41,118	34,437	22,014
Transportation	20,400	28,993	25,107
Depletion, depreciation and accretion (Note 5)	225,033	197,867	131,335
Asset impairment (Note 5)	0	0	1,514
General and administrative	34,730	39,483	39,014
Severance	1,771	2,361	1,287
Equity tax	0	0	1,224
Foreign exchange loss	627	9,957	2,067
Financial instruments (gain) loss (Note 13)	(46,215)	12,296	15,929
Interest expense (Note 6)	43,268	27,364	13,882
TOTAL EXPENSES	462,818	464,030	341,228
OTHER LOSS (Notes 5, 6 and 10)	(12,886)	0	(44,385)
INTEREST INCOME	696	2,086	1,209
INCOME BEFORE INCOME TAXES	95,975	151,487	37,330
INCOME TAX EXPENSE
Current (Note 10)	17,058	43,903	24,322
Deferred (Note 10)	40,227	4,968	44,716
INCOME TAX EXPENSE (RECOVERY)	57,285	48,871	69,038
NET AND COMPREHENSIVE INCOME (LOSS)	$ 38,690	$ 102,616	$ (31,708)
NET INCOME (LOSS) PER SHARE - BASIC (in USD per share)	$ 0.10	$ 0.26	$ (0.08)
NET INCOME (LOSS) PER SHARE - DILUTED (in USD per share)	$ 0.10	$ 0.26	$ (0.08)
WEIGHTED AVERAGE SHARES OUTSTANDING - BASIC (Note 7) (in shares)	376,495,306	390,930,453	396,683,593
WEIGHTED AVERAGE SHARES OUTSTANDING - DILUTED (Note 7) (in shares)	376,507,812	427,119,872	396,683,593

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 8,301	$ 51,040
Restricted cash and cash equivalents (Note 8)	516	1,269
Accounts receivable (Note 4)	36,291	26,177
Investment (Note 13)	94,741	32,724
Taxes receivable	135,838	78,259
Other current assets	15,001	13,056
Total Current Assets	290,688	202,525
Oil and Gas Properties (using the full cost method of accounting)
Proved	1,258,934	853,428
Unproved	310,809	456,598
Total Oil and Gas Properties	1,569,743	1,310,026
Other capital assets	7,650	2,751
Total Property, Plant and Equipment (Notes 5)	1,577,393	1,312,777
Other Long-Term Assets
Taxes receivable	25,869	0
Deferred tax assets (Note 10)	44,003	45,437
Investment (Note 13)	0	8,711
Other long-term assets	4,130	4,553
Goodwill	102,581	102,581
Total Other Long-Term Assets	176,583	161,282
Total Assets	2,044,664	1,676,584
Current Liabilities
Accounts payable and accrued liabilities (Note 11)	195,513	154,670
Derivatives (Note 13)	775	1,017
Taxes payable	0	4,149
Equity compensation award liability (Note 7 and 13)	3,053	9,544
Total Current Liabilities	199,341	169,380
Long-Term Liabilities
Long-term debt (Notes 6)	700,459	399,415
Deferred tax liabilities (Note 10)	59,762	23,419
Asset retirement obligation (Note 8)	43,419	43,676
Equity compensation award liability (Note 7 and 13)	4,806	8,139
Other long-term liabilities	4,267	2,805
Total Long-Term Liabilities	812,713	477,454
Commitments and Contingencies (Note 12)
Shareholders’ Equity
Common Stock (Note 7) (366,981,556 and 387,079,027 shares of Common Stock, par value $0.001 per share, issued and outstanding as at December 31, 2019 and December 31, 2018, respectively)	10,270	10,290
Additional paid in capital	1,282,627	1,318,048
Deficit	(260,287)	(298,588)
Total Shareholders’ Equity	1,032,610	1,029,750
Total Liabilities and Shareholders’ Equity	$ 2,044,664	$ 1,676,584

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common shares, issued (in shares)	366,981,556	387,079,027
Common shares, outstanding (in shares)	366,981,556	387,079,027
Common shares, par value (in dollars per share)	$ 0.001	$ 0.001

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income (loss)	$ 38,690,000	$ 102,616,000	$ (31,708,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depletion, depreciation and accretion (Note 5)	225,033,000	197,867,000	131,335,000
Asset impairment (Note 5)	0	0	1,514,000
Deferred tax expense (Note 10)	40,227,000	4,968,000	44,716,000
Stock-based compensation (Note 7)	1,430,000	8,299,000	9,775,000
Amortization of debt issuance costs (Note 6)	3,376,000	3,183,000	2,415,000
Non-cash lease expenses	1,806,000
Lease payments	(1,969,000)
Cash settlement of restricted share units	0	(360,000)	(564,000)
Unrealized foreign exchange loss	1,803,000	11,511,000	837,000
Financial instruments (gain) loss (Note 13)	(46,215,000)	12,296,000	15,929,000
Cash settlement of financial instruments	(3,273,000)	(33,931,000)	1,563,000
Cash settlement of asset retirement obligation (Note 8)	(870,000)	(519,000)	(1,336,000)
Loss on sale (Note 5)	0	0	44,385,000
Loss on redemption of Convertible Notes (Note 6)	11,501,000	0	0
Net change in assets and liabilities from operating activities (Note 14)	(93,874,000)	(21,421,000)	(29,217,000)
Net cash provided by operating activities	177,665,000	284,509,000	189,644,000
Investing Activities
Additions to property, plant and equipment (Note 5)	(379,314,000)	(347,093,000)	(251,041,000)
Property acquisitions (Note 5)	(77,772,000)	(53,200,000)	(34,410,000)
Net proceeds from sale of business units	0	0	32,968,000
Cash paid for investments	0	0	(11,000,000)
Changes in non-cash investing working capital	(7,851,000)	17,704,000	19,680,000
Net cash used in investing activities	(464,937,000)	(382,589,000)	(243,803,000)
Financing Activities
Proceeds from issuance of Senior Notes, net of issuance costs (Note 6)	289,271,000	288,131,000	0
Proceeds from bank debt, net of issuance costs	342,575,000	4,560,000	167,043,000
Repayment of debt	(349,219,000)	(153,000,000)	(110,000,000)
Proceeds from exercise of stock options	0	1,429,000	0
Repurchase of shares of Common Stock (Note 7)	(37,561,000)	(12,742,000)	(17,916,000)
Net cash provided by financing activities	245,066,000	128,378,000	39,127,000
Foreign exchange loss on cash, cash equivalents and restricted cash and cash equivalents	(1,027,000)	(2,668,000)	(1,557,000)
Net (decrease) increase in cash, cash equivalents and restricted cash and cash equivalents	(43,233,000)	27,630,000	(16,589,000)
Cash and cash equivalents and restricted cash and cash equivalents, beginning of year (Note 14)	54,308,000	26,678,000	43,267,000
Cash and cash equivalents and restricted cash and cash equivalents, end of year (Note 14)	$ 11,075,000	$ 54,308,000	$ 26,678,000

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Share Capital	Additional Paid in Capital	Deficit
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment for accounting changes related to leases and tax reorganizations (Note 2)				$ 124,476
Balance, beginning of year at Dec. 31, 2016		$ 10,303	$ 1,342,656	(493,972)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (Note 7)			0
Stock-based compensation (Note 7)			2,496
Repurchase of Common Stock (Note 7)		(8)	(17,908)
Net income (loss)	$ (31,708)			(31,708)
Balance, end of year at Dec. 31, 2017	936,335	10,295	1,327,244	(401,204)
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment for accounting changes related to leases and tax reorganizations (Note 2)				0
Exercise of stock options (Note 7)			1,429
Stock-based compensation (Note 7)			2,112
Repurchase of Common Stock (Note 7)		(5)	(12,737)
Net income (loss)	102,616			102,616
Balance, end of year at Dec. 31, 2018	1,029,750	10,290	1,318,048	(298,588)
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment for accounting changes related to leases and tax reorganizations (Note 2)				(389)
Exercise of stock options (Note 7)			0
Stock-based compensation (Note 7)			2,120
Repurchase of Common Stock (Note 7)		(20)	(37,541)
Net income (loss)	38,690			38,690
Balance, end of year at Dec. 31, 2019	$ 1,032,610	$ 10,270	$ 1,282,627	$ (260,287)

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies The consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). Significant accounting policies are: Basis of consolidation These consolidated financial statements include the accounts of the Company and its controlled subsidiaries. All intercompany accounts and transactions have been eliminated. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates made by management include: oil and natural gas reserves and related present value of future cash flows; depreciation, depletion, amortization and impairment (“DD&A”); impairment assessments of goodwill; timing of transfers from oil and gas properties not subject to depletion to the depletable base; asset retirement obligations; determining the value of the consideration transferred and the net identifiable assets acquired and liabilities assumed in connection with business combinations and determining goodwill; assessments of the likely outcome of legal and other contingencies; income taxes; stock-based compensation; and determining the fair value of derivatives and investment. Although management believes these estimates are reasonable, changes in facts and circumstances or discovery of new information may result in revised estimates and actual results may differ from these estimates. Cash and cash equivalents The Company considers all highly liquid investments with an original maturity of three months or less to be cash equivalents. Restricted cash and cash equivalents Restricted cash and cash equivalents comprises cash and cash equivalents pledged to secure letters of credit and to settle asset retirement obligations. Letters of credit currently secured by cash relate to work commitment guarantees contained in exploration contracts. Restrictions will lapse when work obligations are satisfied pursuant to the exploration contract or an asset retirement obligation is settled. Cash and claims to cash that are restricted as to withdrawal or use for other than current operations or are designated for expenditure in the acquisition or construction of long-term assets are excluded from the current asset classification. The long-term portion of restricted cash and cash equivalents is included in other long-term assets on the Company's balance sheet. Allowance for doubtful accounts The Company estimates losses on receivables based on known uncollectible accounts, if any, and historical experience of losses incurred and accrues a reserve on a receivable when, based on the judgment of management, it is probable that a receivable will not be collected and the amount of the reserve may be reasonably estimated. Investment in PetroTal Corp. During December 2017, the Company acquired an investment in common shares of PetroTal Corp. ("PetroTal") in connection with the sale of its Peru business unit. At December 31, 2019 , this investment represented approximately 37% of PetroTal's issued and outstanding common shares. The Company determined that it did not have a controlling financial interest in PetroTal, but could exert significant influence over PetroTal's operating and financial policies as a result of its ownership interest in PetroTal and the right to nominate two directors to PetroTal's board of directors. Accordingly, Gran Tierra accounted for its investment in the common shares of PetroTal as an equity method investment, but elected the fair value option for this investment to reflect the value that market participants would use to value the investment. The fair value of the investment in PetroTal's common shares is recorded in 'Investments' in the consolidated balance sheet, and the change in fair value is recorded in the consolidated statements of operations as financial instruments gains or losses. Derivatives The Company records derivative instruments on its balance sheet at fair value as either an asset or liability with changes in fair value recognized in the consolidated statements of operations as financial instruments gains or losses. While the Company utilizes derivative instruments to manage the price risk attributable to its expected oil production and foreign exchange risk, it has elected not to designate its derivative instruments as accounting hedges under the accounting guidance. Inventory Inventory consists of oil in tanks and third party pipelines and supplies and is valued at the lower of cost and net realizable value. The cost of inventory is determined using the weighted average method. Oil inventories include expenditures incurred to produce, upgrade and transport the product to the storage facilities and include operating, depletion and depreciation expenses and cash royalties. Income taxes Income taxes are recognized using the liability method, whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statements carrying amounts of existing assets and liabilities and their respective tax base, and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. Valuation allowances are provided if, after considering available evidence, it is not more likely than not that some or all of the deferred tax assets will be realized. The tax benefit from an uncertain tax position is recognized when it is more likely than not, based on the technical merits of the position, that the position will be sustained on examination by the taxing authorities. Additionally, the amount of the tax benefit recognized is the largest amount of benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. In evaluating whether a tax position has met the more-likely-than-not recognition threshold, the Company presumes that the position will be examined by the appropriate taxing authority that has full knowledge of all relevant information. The Company recognizes potential penalties and interest related to unrecognized tax benefits as a component of income tax expense. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other than Inventory." This ASU requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense or benefit in the period the sale or transfer occurs. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those years. Early adoption was permitted as of the beginning of an annual reporting period. The ASU is required to be applied on a modified retrospective basis with a cumulative-effect adjustment directly to retained earnings in the period of adoption. The Company early adopted this ASU on January 1, 2017, and in the three months ending March 31, 2017, wrote off the income tax effects that had been deferred from past intercompany transactions to opening deficit. A total of $124.5 million , representing deferred tax assets of $178.6 million , net of $54.1 million of prepaid tax, was recorded directly to opening deficit at January 1, 2017. Deferred tax assets recorded upon adoption were assessed for realizability under Accounting Standards Codification ("ASC") 740 "Income Taxes", and, valuation allowances were recognized on those deferred tax assets as necessary on the date of adoption. The adoption of ASU 2016-16 did not have any effect on the Company’s cash flows. Oil and gas properties The Company uses the full cost method of accounting for its investment in oil and natural gas properties as defined by the Securities and Exchange Commission (“SEC”). Under this method, the Company capitalizes all acquisition, exploration and development costs incurred for the purpose of finding oil and natural gas reserves, including salaries, benefits and other internal costs directly attributable to these activities. Costs associated with production and general corporate activities; however, are expensed as incurred. Separate cost centers are maintained for each country in which the Company incurs costs. The Company computes depletion of oil and natural gas properties on a quarterly basis using the unit-of-production method based upon production and estimates of proved reserve quantities. Future development costs related to properties with proved reserves are also included in the amortization base for computation of depletion. The costs of unproved properties are excluded from the amortization base until the properties are evaluated. The cost of exploratory dry wells is transferred to proved properties, and thus is subject to amortization, immediately upon determination that a well is dry in those countries where proved reserves exist. The Company performs a ceiling test calculation each quarter in accordance with SEC Regulation S-X Rule 4-10. In performing its quarterly ceiling test, the Company limits, on a country-by-country basis, the capitalized costs of proved oil and natural gas properties, net of accumulated depletion and deferred income taxes, to the estimated future net cash flows from proved oil and natural gas reserves discounted at 10% , net of related tax effects, plus the lower of cost or fair value of unproved properties included in the costs being amortized. If such capitalized costs exceed the ceiling, the Company will record a write-down to the extent of such excess as a non-cash charge to net income or loss. Any such write-down will reduce earnings in the period of occurrence and results in a lower DD&A rate in future periods. A write-down may not be reversed in future periods even though higher oil and natural gas prices may subsequently increase the ceiling. The Company calculates future net cash flows by applying the unweighted average of prices in effect on the first day of the month for the preceding 12-month period, adjusted for location and quality differentials. Such prices are utilized except where different prices are fixed and determinable from applicable contracts for the remaining term of those contracts. Unproved properties are not depleted pending the determination of the existence of proved reserves. Costs are transferred into the depletable base on an ongoing basis as the properties are evaluated and proved reserves are established or impairment is determined. Unproved properties are evaluated quarterly to ascertain whether impairment has occurred. This evaluation considers, among other factors, seismic data, requirements to relinquish acreage, drilling results and activity, remaining time in the commitment period, remaining capital plans, and political, economic, and market conditions. During any period in which factors indicate an impairment, the cumulative costs incurred to date for such property are transferred to the full cost pool and are then subject to depletion. For countries where a reserve base has not yet been established, the impairment is charged to earnings. In exploration areas, related seismic costs are capitalized in unproved property and evaluated as part of the total capitalized costs associated with a property. Seismic costs related to development projects are recorded in proved properties and therefore subject to depletion as incurred. Gains and losses on the sale or other disposition of oil and natural gas properties are not recognized, unless the gain or loss would significantly alter the relationship between capitalized costs and proved reserves of oil and natural gas attributable to a country. Asset retirement obligation The Company records an estimated liability for future costs associated with the abandonment of its oil and gas properties including the costs of reclamation of drilling sites. The Company records the fair value of a liability for a legal obligation to retire an asset in the period in which the liability is incurred with an offsetting increase to the related oil and gas properties. The fair value of an asset retirement obligation is measured by reference to the expected future cash outflows required to satisfy the retirement obligation discounted at the Company’s credit-adjusted risk-free interest rate. Accretion expense is recognized over time as the discounted liabilities are accreted to their expected settlement value, while the asset retirement cost is amortized over the estimated productive life of the related assets. The accretion of the asset retirement obligation and amortization of the asset retirement cost are included in DD&A. If estimated future costs of an asset retirement obligation change, an adjustment is recorded to both the asset retirement obligation and oil and gas properties. Revisions to the estimated asset retirement obligation can result from changes in retirement cost estimates, revisions to estimated inflation rates and changes in the estimated timing of abandonment. Other capital assets Other capital assets, including additions and replacements, are recorded at cost upon acquisition and include furniture, fixtures and leasehold improvement, computer equipment and automobiles. Depreciation for furniture and fixtures, computer equipment and automobiles is provided using the straight-line method over the useful life of the asset. Leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful life and the term of the related lease. The cost of repairs and maintenance is charged to expense as incurred. Goodwill Goodwill represents the excess of the aggregate of the consideration transferred over the net identifiable assets acquired and liabilities assumed. The Company assesses qualitative factors annually, or more frequently if necessary, to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount and whether it is necessary to perform the goodwill impairment test. The impairment test requires allocating goodwill and certain other assets and liabilities to assigned reporting units. The fair value of each reporting unit is estimated and compared with its net book value. An impairment loss is recognized if the estimated fair value of the reporting unit is less than its carrying amount, not exceeding the carrying amount of goodwill allocated to that reporting unit. Because quoted market prices are not available for the Company’s reporting unit, the fair value of the reporting unit is estimated based upon estimated future cash flows of the reporting unit. The goodwill relates entirely to Colombia. The Company performed step 1 test of goodwill impairment at December 31, 2019 , and no impairment of goodwill was identified. Convertible Notes The Company accounted for its 5.00% Convertible Senior Notes due 2021 (the "Convertible Notes") as a liability in their entirety. The embedded features of the Convertible Notes were assessed for bifurcation from the Convertible Notes under the applicable provisions, including the basic conversion feature, the fundamental change make-whole provision and the put and call options. Based on the assessment, the Company concluded that these embedded features did not meet the criteria to be accounted for separately. The Company incurred debt issuance costs in connection with the issuance of the Convertible Notes which we've presented as a direct deduction against the carrying amount of the Convertible Notes and were amortized to interest expense using the effective interest method. As at December 31, 2019 , there were no Convertible Notes outstanding and all debt issuance costs relating to the Convertible Notes were expensed in the period. Revenue from Contracts with Customers The Company's revenue relates to oil and natural gas sales in Colombia. The Company recognizes revenue when it transfers control of the product to a customer. This generally occurs at the time the customer obtains legal title to the product and when it is physically transferred to the delivery point agreed with the customer. Payment terms are generally within three business days following delivery of an invoice to the customer. Revenue is recognized based on the consideration specified in contracts with customers. Revenue represents the Company's share and is recorded net of royalty payments to governments and other mineral interest owners. The Company evaluates its arrangement with third parties and partners to determine if the Company acts as a principal or an agent. In making this evaluation, management considers if the Company obtains control of the product delivered, which is indicated by the Company having the primary responsibility for the delivery of the product, having ability to establish prices or having inventory risk. If the Company acts in the capacity of an agent rather than as a principal in transaction, then the revenue is recognized on a net-basis, only reflecting the fee realized by the Company from the transaction. Tariffs, tolls and fees charged to other entities for use of pipelines owned by the Company are evaluated by management to determine if these originate from contracts with customers or from incidental arrangements. When determining if the Company acted as a principal or as an agent in transactions, management determines if the Company obtains control of the product. As part of this assessment, management considers detailed criteria for revenue recognition set out in ASC 606. In 2017, revenue from the production of oil and natural gas was recognized when the customer took title and assumed the risks and rewards of ownership, prices were fixed or determinable, the sale was evidenced by a contract and collection of the revenue was reasonably assured. Stock-based compensation The Company records stock-based compensation expense in its consolidated financial statements measured at the fair value of the awards that are ultimately expected to vest. Fair values are determined using pricing models such as the Black-Scholes-Merton or Monte Carlo simulation stock option-pricing models and/or observable share prices. For equity-settled stock-based compensation awards, fair values are determined at the grant date and the expense, net of estimated forfeitures, is recognized using the accelerated method over the requisite service period. An adjustment is made to compensation expense for any difference between the estimated forfeitures and the actual forfeitures. For cash-settled stock-based compensation awards, fair values are determined at each reporting date and periodic changes are recognized as compensation costs, with a corresponding change to liabilities. The Company uses historical data to estimate the expected term used in the Black-Scholes option pricing model, option exercises and employee departure behavior. Expected volatilities used in the fair value estimate are based on the historical volatility of the Company’s shares. The risk-free rate for periods within the expected term of the stock options is based on the U.S. Treasury yield curve in effect at the time of grant. Stock-based compensation expense is capitalized as part of oil and natural gas properties or expensed as part of general and administrative (“G&A”) or operating expenses, as appropriate. Foreign currency translation The functional currency of the Company, including its subsidiaries, is the United States dollar. Monetary items are translated into the reporting currency at the exchange rate in effect at the balance sheet date and non-monetary items are translated at historical exchange rates. Revenue and expense items are translated in a manner that produces substantially the same reporting currency amounts that would have resulted had the underlying transactions been translated on the dates they occurred. DD&A expense on assets is translated at the historical exchange rates similar to the assets to which they relate. Gains and losses resulting from foreign currency transactions, which are transactions denominated in a currency other than the entity’s functional currency, are recognized in net income or loss. Earnings (loss) per share Basic earnings (loss) per share is calculated by dividing net income or loss attributable to common shareholders by the weighted average number of shares of Common Stock and exchangeable shares issued and outstanding during each period. Diluted net income or loss per share is calculated by adjusting the weighted average number of shares of Common Stock and exchangeable shares outstanding for the dilutive effect, if any, of share equivalents. The Company uses the treasury stock method to determine the dilutive effect. This method assumes that all Common Stock equivalents have been exercised at the beginning of the period (or at the time of issuance, if later), and that the funds obtained thereby were used to purchase shares of Common Stock of the Company at the volume weighted average trading price of shares of Common Stock during the period. Recently Adopted Accounting Pronouncements Leases The Company adopted Accounting Standard Codification ("ASC") 842 Leases with a date of initial application on January 1, 2019 in accordance with the modified retrospective transition approach using the practical expedients available for land easements and short-term leases. The Company did not elect the "suite" of practical expedients or use the hindsight expedient in its adoption. At inception of a contract, the Company assesses whether a contract is, or contains, a lease. A contract is, or contains, a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. At inception of a contract that contains a lease component, the Company allocates the consideration in the contract to each lease and non-lease component on the basis of their relative stand-alone prices. The Company recognizes a right-of-use asset and a lease liability at the lease commencement date. The right-of-use asset is initially measured at cost, and subsequently at cost less any accumulated depreciation and impairment losses, and adjusted for certain remeasurements of the lease liability. The lease liability is initially measured at the present value of the lease payments that are not paid at the commencement date, discounted using the interest rate implicit in the lease or, if that rate cannot be readily determined, the Company's incremental borrowing rate. Generally, the Company uses its incremental borrowing rate as the discount rate. The lease liability is subsequently increased by the interest cost on the lease liability and decreased by lease payments made. It is remeasured when there is a change in future lease payments arising from a change in an index or rate, a change in the estimate of the amount expected to be payable under a residual value guarantee, or as appropriate, changes in the assessment of whether a purchase or extension option is reasonably certain to be exercised or a termination option is reasonably certain not to be exercised. The Company has applied judgment to determine the lease term for contracts which include renewal or termination options. The assessment of whether the Company is reasonably certain to exercise such options impacts the lease term, which significantly affects the amount of lease liabilities and right-of-use assets recognized. All leases identified as part of the transition relate to office leases. The transition resulted in the recognition of a right-of-use asset presented in other capital assets of $3.8 million at January 1, 2019, the recognition of lease liabilities of $4.2 million and a $0.4 million impact on retained earnings. When measuring the lease liabilities, the Company's incremental borrowing rate was used. At January 1, 2019 the rates applied ranged between 5.6% and 9.1% . Recently Issued Accounting Pronouncements Financial Instruments - Credit Losses In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses". This ASU replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to support credit loss estimates. In December 2019, the FASB issued ASU 2019-10, "Financial Instruments - Credit Losses, Derivatives and Hedging and Leases", which is codification improvement of ASU 2016-13. The ASU will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. The Company has adopted this ASU on January 1, 2020 and applied a current expected credit loss model that has resulted in no impact on Company's consolidated position, results of operation or cash flows.

Segment and Geographic Reportin

Segment and Geographic Reporting	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment and Geographic Reporting	Segment and Geographic Reporting The Company is primarily engaged in the exploration and production of oil in Colombia. The Company has one reportable segment based on geographic organization, Colombia. For the year ended December 31, 2019 , the Ecuador business unit was not significant and was therefore included in the Colombia reportable segment. Prior to the sale of the Company's Brazil business unit effective June 30, 2017 , and its Peru business unit effective December 18, 2017 , Brazil and Peru were separate reportable segments. The "All Other" category represents the Company’s corporate activities, and the Brazil and Peru activities until the date of sale. The Company evaluates reportable segment performance based on income or loss before income taxes. The following tables present comparative information on the Company’s reportable segment and other activities for the year ended December 31, 2017 : Year Ended December 31, 2017 (Thousands of U.S. Dollars) Colombia All Other Total Oil and natural gas sales $ 413,316 $ 8,418 $ 421,734 DD&A expenses 126,453 4,882 131,335 Asset impairment — 1,514 1,514 General and administrative expenses 23,500 15,514 39,014 Interest expense 486 13,396 13,882 Loss on sale — (44,385 ) (44,385 ) Income (loss) before income taxes 111,829 (74,499 ) 37,330 Segment capital expenditures 242,636 8,405 251,041

Accounts Receivable

Accounts Receivable	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Accounts Receivable	Accounts Receivable As at December 31, (Thousands of U.S. Dollars) 2019 2018 Trade $ 24,890 $ 16,332 Other 11,401 9,845 $ 36,291 $ 26,177

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment As at December 31, (Thousands of U.S. Dollars) 2019 2018 Oil and natural gas properties Proved $ 3,850,565 $ 3,226,811 Unproved 310,809 456,598 4,161,374 3,683,409 Other (1) 26,287 19,549 4,187,661 3,702,958 Accumulated depletion and depreciation (2,610,268 ) (2,390,181 ) $ 1,577,393 $ 1,312,777 (1) Included in other is right-of-use assets for operating and finance leases which totaled $5.7 million as at December 31, 2019 ( December 31, 2018 - nil ). Depletion and depreciation expense on property, plant and equipment for the year ended December 31, 2019 , was $220.8 million ( year ended December 31, 2018 - $197.0 million ; year ended December 31, 2017 - $126.8 million ). A portion of depletion and depreciation expense was recorded as oil inventory in each year. Asset impairment for the three years ended December 31, 2019 , was as follows: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Impairment of oil and gas properties $ — $ — $ 1,514 The Company follows the full cost method of accounting for its oil and gas properties. Under this method, the net book value of properties on a country-by-country basis, less related deferred income taxes, may not exceed a calculated “ceiling”. The ceiling is the estimated after tax future net revenues from proved oil and gas properties, discounted at 10% per year. In calculating discounted future net revenues, oil and natural gas prices are determined using the average price during the 12 months period prior to the ending date of the period covered by the balance sheet, calculated as an unweighted arithmetic average of the first-day-of-the month price for each month within such period for that oil and natural gas. That average price is then held constant, except for changes which are fixed and determinable by existing contracts. Therefore, ceiling test estimates are based on historical prices discounted at 10% per year and it should not be assumed that estimates of future net revenues represent the fair market value of the Company's reserves. In accordance with GAAP, Gran Tierra used an average Brent price of $64.20 per bbl for the purposes of the December 31, 2019 ceiling test calculations ( December 31, 2018 - $72.08 ; December 31, 2017 - $54.19 ). 2019 Acquisitions On February 20, 2019 , the Company acquired 36.2% working interest ("WI") in the Suroriente Block and a 100% WI of the Llanos-5 Block for cash consideration of $79.1 million and a promissory note of $1.5 million included in current accounts payable on the Company's consolidated balance sheet. The cost of the assets was allocated to proved properties using relative fair values. The entire consideration of $0.3 million for Llanos-5 was allocated to unproved properties. (Thousands of U.S. Dollars) Cost of asset acquisition: Cash $ 79,100 Promissory note 1,500 $ 80,600 Allocation of Consideration Paid: Oil and gas properties Proved $ 52,530 Unproved 44,768 97,298 Net working capital (including cash acquired of $5.3 million) (16,698 ) $ 80,600 2018 Acquisitions On October 1, 2018 , the Company acquired the remaining 45% WI in the PUT-1 Block in the Putumayo Basin for cash consideration of $28.1 million , of which $15.2 million was allocated to proved properties. On August 6, 2018 , the Company acquired a WI in the VMM-2 Block in the Middle Magdalena Valley Basin for cash consideration of $17.0 million , of which $6.2 million was allocated to proved properties. On December 1, 2018 , the Company acquired a further WI in the VMM-2 Block for cash consideration of $5.0 million , of which $1.6 million was allocated to proved properties. In total, the Company has acquired an 80% WI in the VMM-2 Block. The Company acquired the remaining 20% WI in the Block in 2019 . On June 20, 2018 , the Company acquired the remaining WI in the Alea 1848-A and 1947-C Blocks in the Putumayo Basin for cash consideration of $3.1 million and was entirely recorded to unproved properties. 2017 Dispositions In 2017 Gran Tierra completed the sale of its Peru and Brazil business units. The net book value of the Peru business unit was greater than proceeds received and resulted in a $34.1 million loss on sale while the net book value of the Brazil business unit was greater than proceeds received and resulted in a $10.2 million loss on sale. Both losses were included in Other Loss. Unproved Oil and Natural Gas Properties At December 31, 2019 , unproved oil and natural gas properties consist of exploration lands held in Colombia and Ecuador. Unproved oil and natural gas properties are being held for their exploration value and are not being depleted pending determination of the existence of proved reserves. Gran Tierra will continue to assess the unproved properties over the next several years as proved reserves are established and as exploration warrants whether or not future areas will be developed. The Company expects that approximately 100% of costs not subject to depletion at December 31, 2019 , will be transferred to the depletable base within the next five years . The following is a summary of Gran Tierra’s oil and natural gas properties not subject to depletion as at December 31, 2019 : Costs Incurred in (Thousands of U.S. Dollars) 2019 2018 2017 Prior to 2017 Total Acquisition costs - Colombia $ 21,773 $ 14,115 $ 10,700 $ 135,202 $ 181,790 Exploration costs - Colombia 56,454 34,349 12,209 22,799 125,811 Exploration costs - Ecuador 3,208 — — — 3,208 $ 81,435 $ 48,464 $ 22,909 $ 158,001 $ 310,809

Debt and Debt Issuance Costs

Debt and Debt Issuance Costs	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt and Debt Issuance Costs	Debt and Debt Issuance Costs The Company's debt at December 31, 2019 and 2018 , was as follows: As at December 31, (Thousands of U.S. Dollars) 2019 2018 6.25% Senior Notes $ 300,000 $ 300,000 7.75% Senior Notes 300,000 — Convertible Notes (b) — 115,000 Revolving credit facility (c) 118,000 — Unamortized debt issuance costs (21,081 ) (15,585 ) Long-term lease obligation (1) 3,540 — Long-term debt $ 700,459 $ 399,415 (1) The current portion of the lease obligation has been included in accounts payable and accrued liabilities on the Company's balance sheet and totaled $3.3 million as at December 31, 2019 ( December 31, 2018 - nil ). Senior Notes On May 20, 2019 , the Company, issued $300.0 million of 7.75% Senior Notes due 2027 (the “ 7.75% Senior Notes”). The 7.75% Senior Notes are fully and unconditionally guaranteed by certain subsidiaries of the Company that guarantee its revolving credit facility. Net proceeds from the issue of the 7.75% Senior Notes were $289.3 million , after deducting the initial purchasers' discounts and commission and the offering expenses payable by the Company. The 7.75% Senior Notes bear interest at a rate of 7.75% per year, payable semi-annually in arrears on May 23 and November 23 of each year, beginning on November 23, 2019 . The 7.75% Senior Notes will mature on May 23, 2027 , unless earlier redeemed or repurchased. Before May 23, 2023 , the Company may, at its option, redeem all or a portion of the 7.75% Senior Notes at 100% of the principal amount plus accrued and unpaid interest and a “make-whole” premium. Thereafter, the Company may redeem all or a portion of the 7.75% Senior Notes plus accrued and unpaid interest applicable to the date of the redemption at the following redemption prices: 2023 - 103.875% ; 2024 - 101.938% ; 2025 and thereafter - 100% . On February 15, 2018 , Gran Tierra Energy International Holdings Ltd. ("GTEIH"), an indirect, wholly-owned subsidiary of the Company, issued $300.0 million of 6.25% Senior Notes due 2025 (the “ 6.25% Senior Notes” and, together with the 7.75% Senior Notes, the “Senior Notes”). The 6.25% Senior Notes are fully and unconditionally guaranteed by the Company and certain subsidiaries of the Company that guarantee its revolving credit facility. Net proceeds from the sale of the 6.25% Senior Notes were $288.1 million , after deducting the initial purchasers' discounts and commission and the offering expenses payable by the Company. The 6.25% Senior Notes bear interest at a rate of 6.25% per year, payable semi-annually in arrears on February 15 and August 15 of each year, beginning on August 15, 2018 . The 6.25% Senior Notes will mature on February 15, 2025 , unless earlier redeemed or repurchased. Before February 15, 2022 , GTEIH may, at its option, redeem all or a portion of the 6.25% Senior Notes at 100% of the principal amount plus accrued and unpaid interest and a make-whole premium. Thereafter, the Company may redeem all or a portion of the 6.25% Senior Notes plus accrued and unpaid interest applicable to the date of the redemption at the following redemption prices: 2022 - 103.125% ; 2023 - 101.563% ; 2024 and thereafter - 100% . Convertible Notes During the year, the Company purchased and canceled $114,999,000 aggregate principal amount of Convertible Notes, including $114,997,000 aggregate principal amount purchased and canceled pursuant to an offer to purchase for cash all outstanding Convertible Notes, at a purchase price of $1,075 in cash per $1,000 principal amount of Convertible Notes plus $1.6 million of accrued and unpaid interest outstanding on such Convertible Notes up to, but not excluding the date of purchase. The Company recorded $11.5 million loss on redemption including the premium paid, transaction costs and the expensing of unamortized deferred financing fees of $2.3 million . At December 31, 2019 , the Company had no Convertible Notes outstanding. Credit Facility At December 31, 2019 , the Company had a revolving credit facility with a syndicate of lenders with a borrowing base of $300.0 million . Availability under the revolving credit facility is determined by the reserves-based borrowing base determined by the lenders. On November 10, 2019, the borrowing base of $300.0 million was reaffirmed and, among other things, the maturity date of the borrowing under the revolving credit facility was extended from November 10, 2021 to November 10, 2022. T he next re-determination of the borrowing base is due to occur no later than May 2020. Amounts drawn down under the revolving credit facility bear interest, at the Company's option, at the USD LIBOR rate plus a margin ranging from 1.65% to 3.65% ( December 31, 2018 - 1.65% to 3.65% ), or an alternate base rate plus a margin ranging from 0.65% to 2.65% ( December 31, 2018 - 0.65% to 2.65% ), in each case based on the borrowing base utilization percentage. The alternate base rate is currently the U.S. prime rate. Undrawn amounts under the revolving credit facility bear interest from 0.41% to 0.91% ( December 31, 2018 - 0.41% to 0.91% ) per annum, based on the average daily amount of unused commitments. The Company’s revolving credit facility is guaranteed by and secured against the assets of certain of the Company’s subsidiaries (the "Credit Facility Group"). Under the terms of the credit facility, the Company is subject on certain restrictions on its ability to distribute funds to entities outside of the Credit Facility Group, including restrictions on the ability to pay dividends to shareholders of the Company. d) Interest expense The following table presents total interest expense recognized in the accompanying consolidated statements of operations: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 2017 Contractual interest and other financing expenses $ 39,892 $ 24,181 $ 11,467 Amortization of debt issuance costs 3,376 3,183 2,415 $ 43,268 $ 27,364 $ 13,882 The Company incurred debt issuance costs in connection with the issuance of the Senior Notes, Convertible Notes and its revolving credit facility. As at December 31, 2019

Share Capital

Share Capital	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Share Capital	Share Capital Shares of Common Stock Exchangeable Shares of Gran Tierra Exchangeco Inc. Exchangeable Shares of Gran Tierra Goldstrike Inc. Balance, December 31, 2016 390,807,194 4,812,592 3,387,302 Shares repurchased and canceled (7,704,381 ) — — Exchange of exchangeable shares 2,088,229 (389,816 ) (1,698,413 ) Balance, December 31, 2017 385,191,042 4,422,776 1,688,889 Options exercised 549,189 — — Shares repurchased and canceled (4,772,869 ) — Exchange of exchangeable shares 6,111,665 (4,422,776 ) (1,688,889 ) Balance, December 31, 2018 387,079,027 — — Shares repurchased and canceled (20,097,471 ) — — Balance, December 31, 2019 366,981,556 — — The Company’s authorized share capital consists of 595,000,000 shares of capital stock, of which 570,000,000 was designated as Common Stock, par value $0.001 per share and 25,000,000 as Preferred Stock, par value $0.001 per share. On July 5, 2018, Gran Tierra Exchangeco Inc., a wholly-owned subsidiary of the Company, redeemed all of its outstanding exchangeable shares which were acquired for purchase consideration of one share of Gran Tierra common stock for each exchangeable share. On July 9, 2018, the Company retired and canceled one share of Special A Voting Stock and one share of Special B Voting Stock, which held voting rights in connection with those exchangeable shares. As a result, no shares of Special A Voting Stock and Special B Voting Stock remain outstanding. The holders of shares of Common Stock are entitled to one vote for each share on all matters submitted to a stockholder vote and are entitled to share in all dividends that the Company’s Board of Directors, in its discretion, declares from legally available funds. The holders of Common Stock have no pre-emptive rights, no conversion rights, and there are no redemption provisions applicable to the shares. Share Repurchase Program In 2019 , the Company implemented a share repurchase program (the “2019 program”) through the facilities of the Toronto Stock Exchange ("TSX") and eligible alternative trading platforms in Canada. Under the 2019 program, the Company is able to purchase at prevailing market prices up to 19,353,951 shares of Common Stock, representing approximately 5% of the issued and outstanding shares of Common Stock as of March 1, 2019 . The 2019 program was scheduled to expire on March 12, 2020 , or earlier if the 5% share maximum is reached. The 2019 program expired when the 5% share maximum was reached in September 2019.The weighted average price per share under the 2019 program was $1.85 per share. All shares purchased were canceled subsequent to the repurchase. During the year ended December 31, 2019 , the Company repurchased 20,097,471 shares of Common Stock at a weighted average price of $1.87 per share. Of the shares repurchased, 743,520 shares at a weighted average price of $2.34 per share were repurchased under 2018 share purchase program implemented in 2018 with similar terms to that of the 2019 program. Equity Compensation Awards The Company has an equity compensation program in place for its executives, employees and directors. Executives and employees are given equity compensation grants that vest based on a recipient's continued employment and in the case of Performance Share Units (“PSUs”), the number of units that vest is dependent upon the achievement of certain key performance measures. Equity settled awards consist 80% of PSUs and 20% of stock options. The Company’s stocked based compensation awards outstanding as at December 31, 2019 , include PSUs, deferred share units (“DSUs”), and stock options. In accordance with the 2007 Equity Incentive Plan, as amended, the Company’s Board of Directors is authorized to issue options or other rights to acquire shares of the Company’s Common Stock. On June 27, 2012, the shareholders of Gran Tierra approved an amendment to the Company’s 2007 Equity Incentive Plan, which increased the Common Stock available for issuance thereunder from 23,306,100 shares to 39,806,100 shares. The following table provides information about PSU, DSU and stock option activity for the year ended December 31, 2019 : PSUs DSUs Stock Options Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Stock Options Weighted Average Exercise Price /Stock Option ($) Balance, December 31, 2018 9,004,661 684,893 9,034,412 $ 3.18 Granted 6,355,214 567,101 2,943,990 2.04 Exercised (2,725,877 ) — — — Forfeited (1,262,631 ) — (1,213,170 ) 3.61 Expired — — (152,360 ) 5.27 Balance, December 31, 2019 11,371,367 1,251,994 10,612,872 $ 2.78 Vested and exercisable, at December 31, 2019 6,469,699 $ 3.14 Vested, or expected to vest, at December 31, 2019 through the life of the options 10,445,530 $ 2.79 Stock-based compensation expense for the year ended December 31, 2019 , was $1.4 million ( December 31, 2018 - $8.3 million ; December 31, 2017 - $9.8 million ) and was primarily recorded in G&A expenses. At December 31, 2019 , there was $6.7 million ( December 31, 2018 - $9.2 million ) of unrecognized compensation cost related to unvested PSUs and stock options which is expected to be recognized over a weighted average period of 1.7 years . The weighted-average remaining contractual term of options vested, or expected to vest, at December 31, 2019 was 2.3 years . PSUs PSUs entitle the holder to receive, at the option of the Company, either the underlying number of shares of the Company's Common Stock upon vesting of such units or a cash payment equal to the value of the underlying shares. PSUs will cliff vest after three years , subject to the continued employment of the grantee. Upon vesting, the underlying number of Common Shares or the cash payment equivalent to their value may range from zero to 200% of the number of PSU's vested, based on the Company’s performance with respect to the applicable performance targets. As at December 31, 2019, 2.4 million (December 31, 2018 - 2.7 million ) of PSU's had vested and will be settled in cash. The performance targets for the PSUs outstanding as at December 31, 2019 , were as follows: (i) 50% of the award is subject to targets relating to the total shareholder return (“TSR”) of the Company against a group of peer companies; (ii) 25% of the award is subject to targets relating to net asset value ("NAV") of the Company per share and NAV is based on before tax net present value discounted at 10% of proved plus probable reserves; and (iii) 25% of the award is subject to targets relating to the execution of corporate strategy. The compensation cost of PSUs is subject to adjustment based upon the attainability of these performance targets. No settlement will occur with respect to the portion of the PSU award subject to each performance target for results below the applicable minimum threshold for that target. PSUs in excess of the target number granted will vest and be settled if performance exceeds the targeted performance goals. The Company currently intends to settle the PSUs in cash. DSUs DSUs entitle the holder to receive, either the underlying number of shares of the Company's Common Stock upon vesting of such units or, at the option of the Company, a cash payment equal to the value of the underlying shares. Once a DSU is vested, it is immediately settled. During the year ended December 31, 2019 , DSUs were granted to directors and will vest 100% at such time the grantee ceases to be a member of the Board of Directors. The Company currently intends to settle the DSUs in cash. Stock Options Each stock option permits the holder to purchase one share of Common Stock at the stated exercise price. The exercise price equals the market price of a share of Common Stock at the time of grant. Stock options generally vest over three years . The term of stock options granted starting in May of 2013 is five years or three months after the grantee’s end of service to the Company, whichever occurs first. Stock options granted prior to May of 2013 continue to have a term of ten years or three months after the end of the grantee’s service to the Company, whichever occurs first. For the year ended December 31, 2019 , no stock options were exercised and no cash proceeds were received ( 2018 – 549,189 options exercised and shares issued; 2017 – no options exercised and no shares issued). At December 31, 2019 , the weighted average remaining contractual term of outstanding stock options was 2.3 years , ( exercisable stock options - 1.3 years ). The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model based on assumptions noted in the following table: Year Ended December 31, 2019 2018 2017 Dividend yield (per share) Nil Nil Nil Volatility 48% to 54% 51% to 55% 51% to 53% Weighted average volatility 51 % 54 % 52 % Risk-free interest rate 1.49% to 2.54% 2.18% to 3.00% 1.75% to 2.10% Expected term 4-5 years 4-5 years 4-5 years The weighted average grant date fair value for options granted in the year ended December 31, 2019 , was $0.89 ( 2018 - $1.15 ; 2017 - $1.11 ). The weighted average grant date fair value for options vested in the year ended December 31, 2019 , was $1.10 ( 2018 - $1.23 ; 2017 - $1.31 ). The total fair value of stock options vested during year ended December 31, 2019 , was $1.9 million ( 2018 - $2.8 million ; 2017 - $2.5 million ). Weighted Average Shares Outstanding Year Ended December 31, 2019 2018 2017 Weighted Average number of common and exchangeable shares outstanding 376,495,306 390,930,453 396,683,593 Shares issuable pursuant to stock options 87,204 4,207,542 — Shares assumed to be purchased from proceeds of stock options (74,698 ) (3,832,516 ) — Shares issuable on conversion of Convertible Notes — 35,814,393 — Weighted average number of diluted common and exchange shares outstanding 376,507,812 427,119,872 396,683,593 For the year ended December 31, 2019 , 9,465,737 options, on a weighted average basis, ( 2018 - 5,354,545 options; 2017 - 9,681,304 options) were excluded from the diluted loss per share calculation as the options were anti-dilutive.

Asset Retirement Obligation

Asset Retirement Obligation	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	Asset Retirement Obligation Changes in the carrying amounts of the asset retirement obligation associated with the Company’s oil and natural gas properties were as follows: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Balance, beginning of year $ 43,799 $ 31,564 Liability incurred 7,034 6,985 Settlements (846 ) (600 ) Accretion 3,436 2,772 Revisions in estimated liability (10,004 ) 2,351 Liabilities assumed in acquisitions — 727 Balance, end of year $ 43,419 $ 43,799 Asset retirement obligation - current $ — $ 123 Asset retirement obligation - long-term 43,419 43,676 Balance, end of year $ 43,419 $ 43,799 Revisions in estimated liabilities relate primarily to changes in estimates of asset retirement costs and include, but are not limited to, revisions of estimated inflation rates, changes in property lives and the expected timing of settling asset retirement obligations. At December 31, 2019 , the fair value of assets that were legally restricted for purposes of settling asset retirement obligations was $2.8 million ( December 31, 2018 - $2.7 million ). These assets were accounted for as restricted cash and cash equivalents on the Company's balance sheet.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Most of the Company's revenue is generated from oil sales at prices which reflect the blended prices received upon shipment by the purchaser at defined sales points or are defined by contract relative to ICE Brent and adjusted for Vasconia or Castilla crude differentials, and quality and transportation discounts each month. For the year ended December 31, 2019 , 100% ( year ended December 31, 2018 - 100% , year-end December 31, 2017 - 99% ) of the Company's revenue resulted from oil sales and quality and transportation discounts were 16% ( year ended December 31, 2018 - 18% , year ended December 31, 2017 - 21% ) of the ICE Brent price. During the year ended December 31, 2019 , the Company's production was sold primarily to three major customers in Colombia ( year ended December 31, 2018 - two , year-end December 31, 2017 - three ). As at December 31, 2019 , accounts receivable included $0.1 million of accrued sales revenue related to December 2019 production (As at December 31, 2018, $4.2 million

Taxes

Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Taxes	Taxes The income tax expense reported differs from the amount computed by applying the statutory rate to loss before income taxes for the following reasons: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 2017 Income (loss) before income taxes United States $ (27,984 ) $ (14,610 ) $ (51,215 ) Foreign 123,959 166,097 88,545 95,975 151,487 37,330 Statutory rate (1) 33 % 37 % 35 % Income tax expense expected 31,672 56,050 13,066 Impact of foreign taxes 9,387 7,011 12,310 Foreign currency translation 11,527 10,336 (118 ) Other local taxes 504 524 1,056 Stock-based compensation 430 324 2,001 Change in valuation allowance 3,429 (21,954 ) 52,269 Non-deductible third party royalty in Colombia 2,240 3,194 3,194 Other permanent differences (1,904 ) (6,614 ) (14,740 ) Total income tax expense $ 57,285 $ 48,871 $ 69,038 Effective tax rate 60 % 32 % 185 % Current income tax expense United States $ — $ — $ 3,457 Foreign 17,058 43,903 20,865 17,058 43,903 24,322 Deferred income tax expense Foreign 40,227 4,968 44,716 Total income tax expense $ 57,285 $ 48,871 $ 69,038 (1) The tax rate in 2019 and 2018 is the statutory rate in Colombia. The tax rate in 2017 is the statutory rate in the U.S. In general, it is the Company's practice and intention to reinvest the earnings of our non-U.S. subsidiaries in such subsidiaries' operations. As of December 31, 2019 , the Company has not made a provision for U.S. or additional foreign withholding taxes on the investments in foreign subsidiaries that are indefinitely reinvested. Generally, such amounts become subject to taxation upon the remittance of dividends and under certain other circumstances. In the fourth quarter of 2019, the Colombia government enacted a new tax reform to replace the 2018 tax reform, which was overturned by the Colombian Constitutional Court. This new tax reform maintains the same corporate tax rates that were approved by Congress in 2018. The enacted corporate tax rates are 32% for 2020, 31% for 2021 and 30% for 2022 and onwards. The tax rates applied to the calculation of deferred income taxes, before valuation allowances, have been adjusted to reflect these changes. As at December 31, (Thousands of U.S. Dollars) 2019 2018 Deferred tax assets Tax benefit of operating loss carryforwards $ 73,096 $ 51,042 Tax basis in excess of book basis 544 8,854 Foreign tax credits and other accruals 76,720 79,820 Tax benefit of capital loss carryforwards 22,710 32,737 Deferred tax assets before valuation allowance 173,070 172,453 Valuation allowance (129,067 ) (127,016 ) 44,003 45,437 Deferred tax liabilities 59,762 23,419 Net deferred tax (liabilities) assets $ (15,759 ) $ 22,018 At December 31, 2019 , the Company has not recognized the benefit of unused non-capital loss carryforwards of $50.5 million (2018 - $22.7 million ) for federal purposes in the United States, which expire from 2029 to 2039. At December 31, 2019 , the Company has not recognized the benefit of unused non-capital loss carryforwards of $31.5 million (2018 - $27.1 million ) for federal and provincial purposes in Canada, which expire from 2025 to 2039. The Company has not recognized the benefit of capital loss carry forwards of $197.5 million (2018 - $242.4 million ) for federal and provincial purposes in Canada which can be carried forward indefinitely. At December 31, 2019 , the Company has recognized the benefit of unused non-capital loss carryforwards of $140.5 million ( 2018 - $99.0 million ), out of a total of $159.2 million and tax credits of $1.5 million ( 2018 - $2.2 million ), out of a total of $3.3 million , for federal purposes in Colombia. As a result of the 2016 Colombian Tax Reform, Colombian losses can be carryforward for a period of 12 years, and not indefinitely as under the previous tax regime. There is a grandfathering rule for losses incurred prior to 2017, which may continue to be carried forward indefinitely. $75.4 million of the Colombian losses can be carried forward indefinitely and $83.8 million are entitled to a carryforward period of 12 years. As at December 31, 2019 and 2018 , Gran Tierra had no unrecognized tax benefits and related interest and penalties included in its deferred and current tax liabilities in the consolidated balance sheet. The Company does not anticipate any material changes with respect to unrecognized tax benefit within the next twelve months. The Company had no other significant interest or penalties related to taxes included in the consolidated statement of operations for the quarter ended December 31, 2019 . The Company and its subsidiaries file income tax returns in the U.S. and certain other foreign jurisdictions. The Company is subject to income tax examinations for the tax years ended 2011 through 2019 in certain jurisdictions. In the fourth quarter of 2019 , $1.4 million

Accounts Payable and Accrued Li

Accounts Payable and Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Trade $ 151,747 $ 123,905 Royalties 5,758 3,550 Employee compensation 6,861 8,195 Other 31,147 19,020 $ 195,513 $ 154,670

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Purchase Obligations, Firm Agreements and Leases As at December 31, 2019 , future minimum payments under non-cancelable agreements with remaining terms in excess of one year were as follows: Year ending December 31 Total 2020 2021 2022 2023 2024 Thereafter (Thousands of U.S. Dollars) Oil transportation services $ 3,211 $ 3,211 $ — $ — $ — $ — $ — Drilling, completions and seismic 21,409 7,602 7,580 6,089 19 20 99 Operating leases (1) 5,679 2,708 1,694 1,277 — — — Finance leases (1) 6,232 2,760 3,192 84 84 84 28 $ 36,531 $ 16,281 $ 12,466 $ 7,450 $ 103 $ 104 $ 127 (1) including maintenance and operating costs Gran Tierra has operating leases for office spaces and finance leases for water flood facilities and storage tanks and commitments relating to compressors, vehicles, equipment and housing. Indemnities Corporate indemnities have been provided by the Company to directors and officers for various items including, but not limited to, all costs to settle suits or actions due to their association with the Company and its subsidiaries and/or affiliates, subject to certain restrictions. The Company has purchased directors’ and officers’ liability insurance to mitigate the cost of any potential future suits or actions. The maximum amount of any potential future payment cannot be reasonably estimated. The Company may provide indemnifications in the normal course of business that are often standard contractual terms to counterparties in certain transactions such as purchase and sale agreements. The terms of these indemnifications will vary based upon the contract, the nature of which prevents the Company from making a reasonable estimate of the maximum potential amounts that may be required to be paid. Letters of Credit At December 31, 2019 , the Company had provided letters of credit and other credit support totaling $120.6 million ( December 31, 2018 - $76.7 million ) as security relating to work commitment guarantees contained in exploration contracts in Colombia and Ecuador and other capital or operating requirements. Contingencies Gran Tierra has a number of lawsuits and claims pending including a dispute with the ANH relating to the calculation of HPR royalties. Although the outcome of these other lawsuits and disputes cannot be predicted with certainty, Gran Tierra believes the resolution of these matters would not have a material adverse effect on the Company’s consolidated financial position, results of operations or cash flows. Gran Tierra records costs as they are incurred or become probable and determinable.

Financial Instruments, Fair Val

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk	Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk Financial Instruments At December 31, 2019 , the Company’s financial instruments recognized in the balance sheet consist of cash and cash equivalents, restricted cash and cash equivalents, accounts receivable, investment, derivatives, accounts payable and accrued liabilities, long-term debt, current and long-term equity compensation reward liability and other long-term liabilities. Fair Value Measurement The fair value of investment, derivatives and PSU liabilities are being remeasured at the estimated fair value at the end of each reporting period. The fair value of the Company's investment in PetroTal was estimated to be $94.7 million as at December 31, 2019 based on the closing stock price of PetroTal of $0.38 or $0.50 CAD per share as at December 31, 2019 ( December 31, 2018 - $0.17 or $ 0.24 CAD per share). The fair value of commodity price and foreign currency derivatives is estimated based on various factors, including quoted market prices in active markets and quotes from third parties. The Company also performs an internal valuation to ensure the reasonableness of third party quotes. In consideration of counterparty credit risk, the Company assessed the possibility of whether the counterparty to the derivative would default by failing to make any contractually required payments. Additionally, the Company considers that it is of substantial credit quality and has the financial resources and willingness to meet its potential repayment obligations associated with the derivative transactions. The fair value of the PSU liability was estimated based on option pricing model using the inputs, such as quoted market prices in an active market, and PSU performance factor. The fair value of investments, derivatives, PSU and DSU liabilities at December 31, 2019 , and December 31, 2018 were as follows: As at December 31, (Thousands of U.S. Dollars) 2019 2018 Investment - current and long-term assets $ 94,741 $ 41,435 $ 94,741 $ 41,435 Derivative liability $ 775 $ 1,017 PSU and DSU liability 7,859 17,683 $ 8,634 $ 18,700 The following table presents gains or losses on financial instruments recognized in the accompanying consolidated statements of operations: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Commodity price derivative loss $ 3,642 $ 13,972 $ 17,327 Foreign currency derivative loss (gain) 27 (890 ) (1,287 ) Investment gain (49,884 ) (786 ) (111 ) $ (46,215 ) $ 12,296 $ 15,929 These gains or losses are presented as financial instruments gains or losses in the consolidated statements of operations and cash flows. GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. This hierarchy consists of three broad levels. Level 1 inputs consist of quoted prices (unadjusted) in active markets for identical assets and liabilities and have the highest priority. Level 2 and 3 inputs are based on significant other observable inputs and significant unobservable inputs, respectively, and have lower priorities. The Company uses appropriate valuation techniques based on the available inputs to measure the fair values of assets and liabilities. Financial instruments not recorded at fair value at December 31, 2019 include the Senior Notes and the Revolving Credit Facility (Note 6). At December 31, 2019 , the carrying amounts of the 6.25% Senior Notes and 7.75% Senior Notes were $290.7 million and $289.9 million , respectively, which represents the aggregate principal amount less unamortized debt issuance costs, and the fair values were $272.8 million and $279.1 million . The fair value of the Revolving Credit Facility approximates its carrying value. The fair value of the Senior Notes is determined based on quoted market prices considered Level 1 inputs. The fair value of the Revolving Credit Facility is estimated based on the amount the Company would have to pay a third party to assume the debt, including the credit spread for the difference between the issue rate and the period end market rate. The credit spread is the Company's default or repayment risk. The credit spread (premium or discount) is determined by comparing the debt to new issuances (secured or unsecured) and secondary trades of similar size and credit statistics for both public and private debt. The fair value of the Revolving Credit Facility was estimated using level 2 inputs. The fair value of long-term restricted cash and cash equivalents and the revolving credit facility approximated their carrying value because interest rates are variable and reflective of market rates. The fair values of other financial instruments approximate their carrying amounts due to the short-term maturity of these instruments. At December 31, 2019 , the fair value of current portion of the investment and DSU liability was determined using Level 1 inputs and the fair value of derivatives and PSUs was determined using Level 2 inputs. The fair value of the long-term portion of the investment restricted by escrow conditions was previously determined using Level 3 inputs. The table below presents a roll-forward of the long-term portion of the investment: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Opening balance $ 8,711 $ 19,147 Transfer from long-term (Level 3) to current (Level 1) (11,881 ) (10,522 ) Unrealized gain on valuation 2,604 846 Unrealized gain (loss) on foreign exchange 566 (760 ) Closing balance $ — $ 8,711 The Company’s non-recurring fair value measurements include asset retirement obligations. The fair value of an asset retirement obligation is measured by reference to the expected future cash outflows required to satisfy the retirement obligation discounted at the Company’s credit-adjusted risk-free interest rate. The significant level 3 inputs used to calculate such liabilities include estimates of costs to be incurred, the Company’s credit-adjusted risk-free interest rate, inflation rates and estimated dates of abandonment. Accretion expense is recognized over time as the discounted liabilities are accreted to their expected settlement value, while the asset retirement cost is amortized over the estimated productive life of the related assets. Commodity Price Risk The Company may at time utilize commodity price derivatives to manage the variability in cash flows associated with the forecasted sale of its oil production, reduce commodity price risk and provide a base level of cash flow in order to assure it can execute at least a portion of its capital spending. As at December 31, 2019 , the Company had outstanding commodity price derivative positions as follows: Period and type of instrument Volume, Reference Purchased Put ($/bbl, Weighted Average) Sold Call ($/bbl, Weighted Average) Premium ($/bbl, Weighted Average) Collars: January 1, to June 30, 2020 6,000 ICE Brent 55.00 69.05 n/a Foreign Exchange Risk The Company is exposed to foreign exchange risk in relation to its Colombian operations predominantly in operating costs, general and administrative costs and transportation costs. To mitigate exposure to fluctuations in foreign exchange, the Company may enter into foreign exchange derivatives. As at December 31, 2019 and subsequent to, the Company had outstanding foreign currency derivative positions as follows: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (Thousands of U.S. Dollars) (1) Reference Floor Price Cap Price (COP, Weighted Average) Collars: January 1, to December 31, 2020 134,500 40,994 COP 3,305 3,423 (1) At December 31, 2019 foreign exchange rate. Unrealized foreign exchange gains and losses primarily result from fluctuation of the U.S. dollar to the Colombian peso due to Gran Tierra’s current and deferred tax liabilities, which are monetary liabilities mainly denominated in the local currency of the Colombian operations. As a result, foreign exchange gains and losses must be calculated on conversion to the U.S. dollar functional currency. A strengthening in the Colombian peso against the U.S. dollar results in foreign exchange gain, estimated at approximately $6,000 for each one peso decrease in the exchange rate of the Colombian peso to one U.S. dollar . This effect was calculated based on the Company's December 31, 2019 , deferred tax balances. For the year ended December 31, 2019 , 100% ( December 31, 2018 - 100% , December 31, 2017 - 98% ) of the Company's oil and natural gas sales were generated in Colombia. In Colombia, the Company receives 100% of its revenues in U.S. dollars and the majority of its capital expenditures are in U.S. dollars or are based on U.S. dollar prices. Credit Risk Credit risk arises from the potential that the Company may incur a loss if counterparty to a financial instrument fails to meet its obligation in accordance with agreed terms. The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents, restricted cash and accounts receivable. The carrying value of cash and cash equivalents, restricted cash and accounts receivable reflects management’s assessment of credit risk . At December 31, 2019 , cash and cash equivalents and restricted cash included balances in bank accounts, term deposits and certificates of deposit, placed with financial institutions with investment grade credit ratings. Most of the Company’s accounts receivable relate to uncollateralized sales to customers in the oil and natural gas industry and are exposed to typical industry credit risks. The concentration of revenues in a single industry affects the Company’s overall exposure to credit risk because customers may be similarly affected by changes in economic and other conditions. The Company manages this credit risk by entering into sales contracts with only credit worthy entities and reviewing its exposure to individual entities on a regular basis. For the year ended December 31, 2019 , the Company had three customers which were over 10% of sales. To reduce the concentration of exposure to any individual counterparty, the Company utilizes a group of investment-grade rated financial institutions, for its derivative transactions. The Company monitors counterparty creditworthiness on an ongoing basis; however, it cannot predict sudden changes in counterparties’ creditworthiness. In addition, even if such changes are not sudden, the Company may be limited in its ability to mitigate an increase in counterparty credit risk. Should one of these counterparties not perform, the Company may not realize the benefit of some of its derivative instruments.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table provides a reconciliation of cash, cash equivalents and restricted cash and cash equivalents with the Company's consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statements of cash flows: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Cash and cash equivalents $ 8,301 $ 51,040 $ 12,326 Restricted cash and cash equivalents - current 516 1,269 11,787 Restricted cash and cash equivalents - long-term (1) 2,258 1,999 2,565 $ 11,075 $ 54,308 $ 26,678 (1) The long-term portion of restricted cash is included in other long-term assets on the Company's balance sheet. Net changes in assets and liabilities from operating activities were as follows: Year Ended December 31, 2019 2018 2017 Accounts receivable and other long-term assets $ (5,680 ) $ 17,674 $ (2,494 ) Derivatives (638 ) 1,017 — Inventory (3,179 ) (2,127 ) (78 ) Other prepaids 583 547 2,674 Accounts payable and accrued and other long-term liabilities (1,367 ) 9,034 15,617 Prepaid tax and taxes receivable and payable (83,593 ) (47,566 ) (44,936 ) Net changes in assets and liabilities from operating activities $ (93,874 ) $ (21,421 ) $ (29,217 ) The following table provides additional supplemental cash flow disclosures: Year Ended December 31, 2019 2018 2017 Cash paid for income taxes $ 49,196 $ 46,277 $ 54,505 Cash paid for interest $ 37,767 $ 16,038 $ 9,684 Non-cash investing activities: Net liabilities related to property, plant and equipment, end of year $ 77,353 $ 85,204 $ 76,352

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of consolidation	Basis of consolidation These consolidated financial statements include the accounts of the Company and its controlled subsidiaries. All intercompany accounts and transactions have been eliminated.
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates made by management include: oil and natural gas reserves and related present value of future cash flows; depreciation, depletion, amortization and impairment (“DD&A”); impairment assessments of goodwill; timing of transfers from oil and gas properties not subject to depletion to the depletable base; asset retirement obligations; determining the value of the consideration transferred and the net identifiable assets acquired and liabilities assumed in connection with business combinations and determining goodwill; assessments of the likely outcome of legal and other contingencies; income taxes; stock-based compensation; and determining the fair value of derivatives and investment. Although management believes these estimates are reasonable, changes in facts and circumstances or discovery of new information may result in revised estimates and actual results may differ from these estimates.
Cash and cash equivalents	Cash and cash equivalents The Company considers all highly liquid investments with an original maturity of three months or less to be cash equivalents.
Restricted cash and cash equivalents	Restricted cash and cash equivalents Restricted cash and cash equivalents comprises cash and cash equivalents pledged to secure letters of credit and to settle asset retirement obligations. Letters of credit currently secured by cash relate to work commitment guarantees contained in exploration contracts. Restrictions will lapse when work obligations are satisfied pursuant to the exploration contract or an asset retirement obligation is settled. Cash and claims to cash that are restricted as to withdrawal or use for other than current operations or are designated for expenditure in the acquisition or construction of long-term assets are excluded from the current asset classification. The long-term portion of restricted cash and cash equivalents is included in other long-term assets on the Company's balance sheet.
Allowance for doubtful accounts	Allowance for doubtful accounts
Investment in PetroTal Corp	Investment in PetroTal Corp. During December 2017, the Company acquired an investment in common shares of PetroTal Corp. ("PetroTal") in connection with the sale of its Peru business unit. At December 31, 2019 , this investment represented approximately 37% of PetroTal's issued and outstanding common shares. The Company determined that it did not have a controlling financial interest in PetroTal, but could exert significant influence over PetroTal's operating and financial policies as a result of its ownership interest in PetroTal and the right to nominate two directors to PetroTal's board of directors. Accordingly, Gran Tierra accounted for its investment in the common shares of PetroTal as an equity method investment, but elected the fair value option for this investment to reflect the value that market participants would use to value the investment. The fair value of the investment in PetroTal's common shares is recorded in 'Investments' in the consolidated balance sheet, and the change in fair value is recorded in the consolidated statements of operations as financial instruments gains or losses.
Derivatives	Derivatives The Company records derivative instruments on its balance sheet at fair value as either an asset or liability with changes in fair value recognized in the consolidated statements of operations as financial instruments gains or losses. While the Company utilizes derivative instruments to manage the price risk attributable to its expected oil production and foreign exchange risk, it has elected not to designate its derivative instruments as accounting hedges under the accounting guidance.
Inventory	Inventory
Income taxes	Income taxes Income taxes are recognized using the liability method, whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statements carrying amounts of existing assets and liabilities and their respective tax base, and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. Valuation allowances are provided if, after considering available evidence, it is not more likely than not that some or all of the deferred tax assets will be realized. The tax benefit from an uncertain tax position is recognized when it is more likely than not, based on the technical merits of the position, that the position will be sustained on examination by the taxing authorities. Additionally, the amount of the tax benefit recognized is the largest amount of benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. In evaluating whether a tax position has met the more-likely-than-not recognition threshold, the Company presumes that the position will be examined by the appropriate taxing authority that has full knowledge of all relevant information. The Company recognizes potential penalties and interest related to unrecognized tax benefits as a component of income tax expense. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other than Inventory." This ASU requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense or benefit in the period the sale or transfer occurs. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those years. Early adoption was permitted as of the beginning of an annual reporting period. The ASU is required to be applied on a modified retrospective basis with a cumulative-effect adjustment directly to retained earnings in the period of adoption. The Company early adopted this ASU on January 1, 2017, and in the three months ending March 31, 2017, wrote off the income tax effects that had been deferred from past intercompany transactions to opening deficit. A total of $124.5 million , representing deferred tax assets of $178.6 million , net of $54.1 million of prepaid tax, was recorded directly to opening deficit at January 1, 2017. Deferred tax assets recorded upon adoption were assessed for realizability under Accounting Standards Codification ("ASC") 740 "Income Taxes", and, valuation allowances were recognized on those deferred tax assets as necessary on the date of adoption. The adoption of ASU 2016-16 did not have any effect on the Company’s cash flows.
Oil and gas properties	Oil and gas properties The Company uses the full cost method of accounting for its investment in oil and natural gas properties as defined by the Securities and Exchange Commission (“SEC”). Under this method, the Company capitalizes all acquisition, exploration and development costs incurred for the purpose of finding oil and natural gas reserves, including salaries, benefits and other internal costs directly attributable to these activities. Costs associated with production and general corporate activities; however, are expensed as incurred. Separate cost centers are maintained for each country in which the Company incurs costs. The Company computes depletion of oil and natural gas properties on a quarterly basis using the unit-of-production method based upon production and estimates of proved reserve quantities. Future development costs related to properties with proved reserves are also included in the amortization base for computation of depletion. The costs of unproved properties are excluded from the amortization base until the properties are evaluated. The cost of exploratory dry wells is transferred to proved properties, and thus is subject to amortization, immediately upon determination that a well is dry in those countries where proved reserves exist. The Company performs a ceiling test calculation each quarter in accordance with SEC Regulation S-X Rule 4-10. In performing its quarterly ceiling test, the Company limits, on a country-by-country basis, the capitalized costs of proved oil and natural gas properties, net of accumulated depletion and deferred income taxes, to the estimated future net cash flows from proved oil and natural gas reserves discounted at 10% , net of related tax effects, plus the lower of cost or fair value of unproved properties included in the costs being amortized. If such capitalized costs exceed the ceiling, the Company will record a write-down to the extent of such excess as a non-cash charge to net income or loss. Any such write-down will reduce earnings in the period of occurrence and results in a lower DD&A rate in future periods. A write-down may not be reversed in future periods even though higher oil and natural gas prices may subsequently increase the ceiling. The Company calculates future net cash flows by applying the unweighted average of prices in effect on the first day of the month for the preceding 12-month period, adjusted for location and quality differentials. Such prices are utilized except where different prices are fixed and determinable from applicable contracts for the remaining term of those contracts. Unproved properties are not depleted pending the determination of the existence of proved reserves. Costs are transferred into the depletable base on an ongoing basis as the properties are evaluated and proved reserves are established or impairment is determined. Unproved properties are evaluated quarterly to ascertain whether impairment has occurred. This evaluation considers, among other factors, seismic data, requirements to relinquish acreage, drilling results and activity, remaining time in the commitment period, remaining capital plans, and political, economic, and market conditions. During any period in which factors indicate an impairment, the cumulative costs incurred to date for such property are transferred to the full cost pool and are then subject to depletion. For countries where a reserve base has not yet been established, the impairment is charged to earnings. In exploration areas, related seismic costs are capitalized in unproved property and evaluated as part of the total capitalized costs associated with a property. Seismic costs related to development projects are recorded in proved properties and therefore subject to depletion as incurred. Gains and losses on the sale or other disposition of oil and natural gas properties are not recognized, unless the gain or loss would significantly alter the relationship between capitalized costs and proved reserves of oil and natural gas attributable to a country.
Asset retirement obligation	Asset retirement obligation The Company records an estimated liability for future costs associated with the abandonment of its oil and gas properties including the costs of reclamation of drilling sites. The Company records the fair value of a liability for a legal obligation to retire an asset in the period in which the liability is incurred with an offsetting increase to the related oil and gas properties. The fair value of an asset retirement obligation is measured by reference to the expected future cash outflows required to satisfy the retirement obligation discounted at the Company’s credit-adjusted risk-free interest rate. Accretion expense is recognized over time as the discounted liabilities are accreted to their expected settlement value, while the asset retirement cost is amortized over the estimated productive life of the related assets. The accretion of the asset retirement obligation and amortization of the asset retirement cost are included in DD&A. If estimated future costs of an asset retirement obligation change, an adjustment is recorded to both the asset retirement obligation and oil and gas properties. Revisions to the estimated asset retirement obligation can result from changes in retirement cost estimates, revisions to estimated inflation rates and changes in the estimated timing of abandonment.
Other capital assets	Other capital assets Other capital assets, including additions and replacements, are recorded at cost upon acquisition and include furniture, fixtures and leasehold improvement, computer equipment and automobiles. Depreciation for furniture and fixtures, computer equipment and automobiles is provided using the straight-line method over the useful life of the asset. Leasehold improvements are depreciated on a straight-line basis over the shorter of the estimated useful life and the term of the related lease. The cost of repairs and maintenance is charged to expense as incurred.
Goodwill	Goodwill Goodwill represents the excess of the aggregate of the consideration transferred over the net identifiable assets acquired and liabilities assumed. The Company assesses qualitative factors annually, or more frequently if necessary, to determine whether it
Convertible Notes	Convertible Notes The Company accounted for its 5.00% Convertible Senior Notes due 2021 (the "Convertible Notes") as a liability in their entirety. The embedded features of the Convertible Notes were assessed for bifurcation from the Convertible Notes under the applicable provisions, including the basic conversion feature, the fundamental change make-whole provision and the put and call options. Based on the assessment, the Company concluded that these embedded features did not meet the criteria to be accounted for separately.
Revenue from Contracts with Customers	Revenue from Contracts with Customers The Company's revenue relates to oil and natural gas sales in Colombia. The Company recognizes revenue when it transfers control of the product to a customer. This generally occurs at the time the customer obtains legal title to the product and when it is physically transferred to the delivery point agreed with the customer. Payment terms are generally within three business days following delivery of an invoice to the customer. Revenue is recognized based on the consideration specified in contracts with customers. Revenue represents the Company's share and is recorded net of royalty payments to governments and other mineral interest owners. The Company evaluates its arrangement with third parties and partners to determine if the Company acts as a principal or an agent. In making this evaluation, management considers if the Company obtains control of the product delivered, which is indicated by the Company having the primary responsibility for the delivery of the product, having ability to establish prices or having inventory risk. If the Company acts in the capacity of an agent rather than as a principal in transaction, then the revenue is recognized on a net-basis, only reflecting the fee realized by the Company from the transaction. Tariffs, tolls and fees charged to other entities for use of pipelines owned by the Company are evaluated by management to determine if these originate from contracts with customers or from incidental arrangements. When determining if the Company acted as a principal or as an agent in transactions, management determines if the Company obtains control of the product. As part of this assessment, management considers detailed criteria for revenue recognition set out in ASC 606. In 2017, revenue from the production of oil and natural gas was recognized when the customer took title and assumed the risks and rewards of ownership, prices were fixed or determinable, the sale was evidenced by a contract and collection of the revenue was reasonably assured.
Stock-based compensation	Stock-based compensation The Company records stock-based compensation expense in its consolidated financial statements measured at the fair value of the awards that are ultimately expected to vest. Fair values are determined using pricing models such as the Black-Scholes-Merton or Monte Carlo simulation stock option-pricing models and/or observable share prices. For equity-settled stock-based compensation awards, fair values are determined at the grant date and the expense, net of estimated forfeitures, is recognized using the accelerated method over the requisite service period. An adjustment is made to compensation expense for any difference between the estimated forfeitures and the actual forfeitures. For cash-settled stock-based compensation awards, fair values are determined at each reporting date and periodic changes are recognized as compensation costs, with a corresponding change to liabilities. The Company uses historical data to estimate the expected term used in the Black-Scholes option pricing model, option exercises and employee departure behavior. Expected volatilities used in the fair value estimate are based on the historical volatility of the Company’s shares. The risk-free rate for periods within the expected term of the stock options is based on the U.S. Treasury yield curve in effect at the time of grant. Stock-based compensation expense is capitalized as part of oil and natural gas properties or expensed as part of general and administrative (“G&A”) or operating expenses, as appropriate.
Foreign currency translation	Foreign currency translation The functional currency of the Company, including its subsidiaries, is the United States dollar. Monetary items are translated into the reporting currency at the exchange rate in effect at the balance sheet date and non-monetary items are translated at historical exchange rates. Revenue and expense items are translated in a manner that produces substantially the same reporting currency amounts that would have resulted had the underlying transactions been translated on the dates they occurred. DD&A expense on assets is translated at the historical exchange rates similar to the assets to which they relate. Gains and losses resulting from foreign currency transactions, which are transactions denominated in a currency other than the entity’s functional currency, are recognized in net income or loss.
Earnings (loss) per share	Earnings (loss) per share Basic earnings (loss) per share is calculated by dividing net income or loss attributable to common shareholders by the weighted average number of shares of Common Stock and exchangeable shares issued and outstanding during each period. Diluted net income or loss per share is calculated by adjusting the weighted average number of shares of Common Stock and exchangeable shares outstanding for the dilutive effect, if any, of share equivalents. The Company uses the treasury stock method to determine the dilutive effect. This method assumes that all Common Stock equivalents have been exercised at the beginning of the period (or at the time of issuance, if later), and that the funds obtained thereby were used to purchase shares of Common Stock of the Company at the volume weighted average trading price of shares of Common Stock during the period.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Leases The Company adopted Accounting Standard Codification ("ASC") 842 Leases with a date of initial application on January 1, 2019 in accordance with the modified retrospective transition approach using the practical expedients available for land easements and short-term leases. The Company did not elect the "suite" of practical expedients or use the hindsight expedient in its adoption. At inception of a contract, the Company assesses whether a contract is, or contains, a lease. A contract is, or contains, a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. At inception of a contract that contains a lease component, the Company allocates the consideration in the contract to each lease and non-lease component on the basis of their relative stand-alone prices. The Company recognizes a right-of-use asset and a lease liability at the lease commencement date. The right-of-use asset is initially measured at cost, and subsequently at cost less any accumulated depreciation and impairment losses, and adjusted for certain remeasurements of the lease liability. The lease liability is initially measured at the present value of the lease payments that are not paid at the commencement date, discounted using the interest rate implicit in the lease or, if that rate cannot be readily determined, the Company's incremental borrowing rate. Generally, the Company uses its incremental borrowing rate as the discount rate. The lease liability is subsequently increased by the interest cost on the lease liability and decreased by lease payments made. It is remeasured when there is a change in future lease payments arising from a change in an index or rate, a change in the estimate of the amount expected to be payable under a residual value guarantee, or as appropriate, changes in the assessment of whether a purchase or extension option is reasonably certain to be exercised or a termination option is reasonably certain not to be exercised. The Company has applied judgment to determine the lease term for contracts which include renewal or termination options. The assessment of whether the Company is reasonably certain to exercise such options impacts the lease term, which significantly affects the amount of lease liabilities and right-of-use assets recognized. All leases identified as part of the transition relate to office leases. The transition resulted in the recognition of a right-of-use asset presented in other capital assets of $3.8 million at January 1, 2019, the recognition of lease liabilities of $4.2 million and a $0.4 million impact on retained earnings. When measuring the lease liabilities, the Company's incremental borrowing rate was used. At January 1, 2019 the rates applied ranged between 5.6% and 9.1% . Recently Issued Accounting Pronouncements Financial Instruments - Credit Losses In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses". This ASU replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to support credit loss estimates. In December 2019, the FASB issued ASU 2019-10, "Financial Instruments - Credit Losses, Derivatives and Hedging and Leases", which is codification improvement of ASU 2016-13. The ASU will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2019. The Company has adopted this ASU on January 1, 2020 and applied a current expected credit loss model that has resulted in no impact on Company's consolidated position, results of operation or cash flows.

Segment and Geographic Report_2

Segment and Geographic Reporting (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Schedule of Information on Reportable Segments and Other Activities	The following tables present comparative information on the Company’s reportable segment and other activities for the year ended December 31, 2017 : Year Ended December 31, 2017 (Thousands of U.S. Dollars) Colombia All Other Total Oil and natural gas sales $ 413,316 $ 8,418 $ 421,734 DD&A expenses 126,453 4,882 131,335 Asset impairment — 1,514 1,514 General and administrative expenses 23,500 15,514 39,014 Interest expense 486 13,396 13,882 Loss on sale — (44,385 ) (44,385 ) Income (loss) before income taxes 111,829 (74,499 ) 37,330 Segment capital expenditures 242,636 8,405 251,041

Accounts Receivable (Tables)

Accounts Receivable (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Schedule of Accounts Receivable	As at December 31, (Thousands of U.S. Dollars) 2019 2018 Trade $ 24,890 $ 16,332 Other 11,401 9,845 $ 36,291 $ 26,177

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	As at December 31, (Thousands of U.S. Dollars) 2019 2018 Oil and natural gas properties Proved $ 3,850,565 $ 3,226,811 Unproved 310,809 456,598 4,161,374 3,683,409 Other (1) 26,287 19,549 4,187,661 3,702,958 Accumulated depletion and depreciation (2,610,268 ) (2,390,181 ) $ 1,577,393 $ 1,312,777 (1) Included in other is right-of-use assets for operating and finance leases which totaled $5.7 million as at December 31, 2019 ( December 31, 2018 - nil ).
Schedule of Asset Impairment	Asset impairment for the three years ended December 31, 2019 , was as follows: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Impairment of oil and gas properties $ — $ — $ 1,514
Schedule of Asset Acquisition	(Thousands of U.S. Dollars) Cost of asset acquisition: Cash $ 79,100 Promissory note 1,500 $ 80,600 Allocation of Consideration Paid: Oil and gas properties Proved $ 52,530 Unproved 44,768 97,298 Net working capital (including cash acquired of $5.3 million) (16,698 ) $ 80,600
Summary of Oil and Natural Gas Properties	The following is a summary of Gran Tierra’s oil and natural gas properties not subject to depletion as at December 31, 2019 : Costs Incurred in (Thousands of U.S. Dollars) 2019 2018 2017 Prior to 2017 Total Acquisition costs - Colombia $ 21,773 $ 14,115 $ 10,700 $ 135,202 $ 181,790 Exploration costs - Colombia 56,454 34,349 12,209 22,799 125,811 Exploration costs - Ecuador 3,208 — — — 3,208 $ 81,435 $ 48,464 $ 22,909 $ 158,001 $ 310,809

Debt and Debt Issuance Costs (T

Debt and Debt Issuance Costs (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Debt	The Company's debt at December 31, 2019 and 2018 , was as follows: As at December 31, (Thousands of U.S. Dollars) 2019 2018 6.25% Senior Notes $ 300,000 $ 300,000 7.75% Senior Notes 300,000 — Convertible Notes (b) — 115,000 Revolving credit facility (c) 118,000 — Unamortized debt issuance costs (21,081 ) (15,585 ) Long-term lease obligation (1) 3,540 — Long-term debt $ 700,459 $ 399,415 (1) The current portion of the lease obligation has been included in accounts payable and accrued liabilities on the Company's balance sheet and totaled $3.3 million as at December 31, 2019 ( December 31, 2018 - nil ).
Schedule of Total Interest Expense Recognized	The following table presents total interest expense recognized in the accompanying consolidated statements of operations: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 2017 Contractual interest and other financing expenses $ 39,892 $ 24,181 $ 11,467 Amortization of debt issuance costs 3,376 3,183 2,415 $ 43,268 $ 27,364 $ 13,882

Share Capital (Tables)

Share Capital (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of Common Stock	Shares of Common Stock Exchangeable Shares of Gran Tierra Exchangeco Inc. Exchangeable Shares of Gran Tierra Goldstrike Inc. Balance, December 31, 2016 390,807,194 4,812,592 3,387,302 Shares repurchased and canceled (7,704,381 ) — — Exchange of exchangeable shares 2,088,229 (389,816 ) (1,698,413 ) Balance, December 31, 2017 385,191,042 4,422,776 1,688,889 Options exercised 549,189 — — Shares repurchased and canceled (4,772,869 ) — Exchange of exchangeable shares 6,111,665 (4,422,776 ) (1,688,889 ) Balance, December 31, 2018 387,079,027 — — Shares repurchased and canceled (20,097,471 ) — — Balance, December 31, 2019 366,981,556 — —
Schedule of Information About PSU, DSU, RSU and Stock Option Activity	The following table provides information about PSU, DSU and stock option activity for the year ended December 31, 2019 : PSUs DSUs Stock Options Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Stock Options Weighted Average Exercise Price /Stock Option ($) Balance, December 31, 2018 9,004,661 684,893 9,034,412 $ 3.18 Granted 6,355,214 567,101 2,943,990 2.04 Exercised (2,725,877 ) — — — Forfeited (1,262,631 ) — (1,213,170 ) 3.61 Expired — — (152,360 ) 5.27 Balance, December 31, 2019 11,371,367 1,251,994 10,612,872 $ 2.78 Vested and exercisable, at December 31, 2019 6,469,699 $ 3.14 Vested, or expected to vest, at December 31, 2019 through the life of the options 10,445,530 $ 2.79
Schedule of Assumptions Using the Black-Scholes Option Pricing Model	The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model based on assumptions noted in the following table: Year Ended December 31, 2019 2018 2017 Dividend yield (per share) Nil Nil Nil Volatility 48% to 54% 51% to 55% 51% to 53% Weighted average volatility 51 % 54 % 52 % Risk-free interest rate 1.49% to 2.54% 2.18% to 3.00% 1.75% to 2.10% Expected term 4-5 years 4-5 years 4-5 years
Schedule of Weighted Average Number of Shares	Weighted Average Shares Outstanding Year Ended December 31, 2019 2018 2017 Weighted Average number of common and exchangeable shares outstanding 376,495,306 390,930,453 396,683,593 Shares issuable pursuant to stock options 87,204 4,207,542 — Shares assumed to be purchased from proceeds of stock options (74,698 ) (3,832,516 ) — Shares issuable on conversion of Convertible Notes — 35,814,393 — Weighted average number of diluted common and exchange shares outstanding 376,507,812 427,119,872 396,683,593

Asset Retirement Obligation (Ta

Asset Retirement Obligation (Tables)	12 Months Ended
	Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Asset Retirement Obligation	Changes in the carrying amounts of the asset retirement obligation associated with the Company’s oil and natural gas properties were as follows: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Balance, beginning of year $ 43,799 $ 31,564 Liability incurred 7,034 6,985 Settlements (846 ) (600 ) Accretion 3,436 2,772 Revisions in estimated liability (10,004 ) 2,351 Liabilities assumed in acquisitions — 727 Balance, end of year $ 43,419 $ 43,799 Asset retirement obligation - current $ — $ 123 Asset retirement obligation - long-term 43,419 43,676 Balance, end of year $ 43,419 $ 43,799

Taxes (Tables)

Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense Reported	The income tax expense reported differs from the amount computed by applying the statutory rate to loss before income taxes for the following reasons: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 2017 Income (loss) before income taxes United States $ (27,984 ) $ (14,610 ) $ (51,215 ) Foreign 123,959 166,097 88,545 95,975 151,487 37,330 Statutory rate (1) 33 % 37 % 35 % Income tax expense expected 31,672 56,050 13,066 Impact of foreign taxes 9,387 7,011 12,310 Foreign currency translation 11,527 10,336 (118 ) Other local taxes 504 524 1,056 Stock-based compensation 430 324 2,001 Change in valuation allowance 3,429 (21,954 ) 52,269 Non-deductible third party royalty in Colombia 2,240 3,194 3,194 Other permanent differences (1,904 ) (6,614 ) (14,740 ) Total income tax expense $ 57,285 $ 48,871 $ 69,038 Effective tax rate 60 % 32 % 185 % Current income tax expense United States $ — $ — $ 3,457 Foreign 17,058 43,903 20,865 17,058 43,903 24,322 Deferred income tax expense Foreign 40,227 4,968 44,716 Total income tax expense $ 57,285 $ 48,871 $ 69,038 (1) The tax rate in 2019 and 2018 is the statutory rate in Colombia. The tax rate in 2017 is the statutory rate in the U.S.
Schedule of Deferred Tax Assets and Liabilities	As at December 31, (Thousands of U.S. Dollars) 2019 2018 Deferred tax assets Tax benefit of operating loss carryforwards $ 73,096 $ 51,042 Tax basis in excess of book basis 544 8,854 Foreign tax credits and other accruals 76,720 79,820 Tax benefit of capital loss carryforwards 22,710 32,737 Deferred tax assets before valuation allowance 173,070 172,453 Valuation allowance (129,067 ) (127,016 ) 44,003 45,437 Deferred tax liabilities 59,762 23,419 Net deferred tax (liabilities) assets $ (15,759 ) $ 22,018

Accounts Payable and Accrued _2

Accounts Payable and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Trade $ 151,747 $ 123,905 Royalties 5,758 3,550 Employee compensation 6,861 8,195 Other 31,147 19,020 $ 195,513 $ 154,670

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Under Non-Cancelable Agreements	As at December 31, 2019 , future minimum payments under non-cancelable agreements with remaining terms in excess of one year were as follows: Year ending December 31 Total 2020 2021 2022 2023 2024 Thereafter (Thousands of U.S. Dollars) Oil transportation services $ 3,211 $ 3,211 $ — $ — $ — $ — $ — Drilling, completions and seismic 21,409 7,602 7,580 6,089 19 20 99 Operating leases (1) 5,679 2,708 1,694 1,277 — — — Finance leases (1) 6,232 2,760 3,192 84 84 84 28 $ 36,531 $ 16,281 $ 12,466 $ 7,450 $ 103 $ 104 $ 127 (1) including maintenance and operating costs

Financial Instruments, Fair V_2

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Trading Securities, Derivative Assets, and RSU and PSU Liabilities	The fair value of investments, derivatives, PSU and DSU liabilities at December 31, 2019 , and December 31, 2018 were as follows: As at December 31, (Thousands of U.S. Dollars) 2019 2018 Investment - current and long-term assets $ 94,741 $ 41,435 $ 94,741 $ 41,435 Derivative liability $ 775 $ 1,017 PSU and DSU liability 7,859 17,683 $ 8,634 $ 18,700
Schedule of Losses or Gains on Financial Instruments Recognized	The following table presents gains or losses on financial instruments recognized in the accompanying consolidated statements of operations: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Commodity price derivative loss $ 3,642 $ 13,972 $ 17,327 Foreign currency derivative loss (gain) 27 (890 ) (1,287 ) Investment gain (49,884 ) (786 ) (111 ) $ (46,215 ) $ 12,296 $ 15,929
Schedule of the Rollforward of Level 3 Financial Assets and Liabilities:	The table below presents a roll-forward of the long-term portion of the investment: Year Ended December 31, (Thousands of U.S. Dollars) 2019 2018 Opening balance $ 8,711 $ 19,147 Transfer from long-term (Level 3) to current (Level 1) (11,881 ) (10,522 ) Unrealized gain on valuation 2,604 846 Unrealized gain (loss) on foreign exchange 566 (760 ) Closing balance $ — $ 8,711
Schedule of Price Risk Derivatives	As at December 31, 2019 , the Company had outstanding commodity price derivative positions as follows: Period and type of instrument Volume, Reference Purchased Put ($/bbl, Weighted Average) Sold Call ($/bbl, Weighted Average) Premium ($/bbl, Weighted Average) Collars: January 1, to June 30, 2020 6,000 ICE Brent 55.00 69.05 n/a
Schedule of Derivative Instruments	As at December 31, 2019 and subsequent to, the Company had outstanding foreign currency derivative positions as follows: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (Thousands of U.S. Dollars) (1) Reference Floor Price Cap Price (COP, Weighted Average) Collars: January 1, to December 31, 2020 134,500 40,994 COP 3,305 3,423 (1) At December 31, 2019 foreign exchange rate.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Summary of Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash and cash equivalents with the Company's consolidated balance sheet that sum to the total of the same such amounts shown in the consolidated statements of cash flows: (Thousands of U.S. Dollars) Year Ended December 31, 2019 2018 2017 Cash and cash equivalents $ 8,301 $ 51,040 $ 12,326 Restricted cash and cash equivalents - current 516 1,269 11,787 Restricted cash and cash equivalents - long-term (1) 2,258 1,999 2,565 $ 11,075 $ 54,308 $ 26,678 (1) The long-term portion of restricted cash is included in other long-term assets on the Company's balance sheet.
Schedule of Net Changes in Assets and Liabilities	Net changes in assets and liabilities from operating activities were as follows: Year Ended December 31, 2019 2018 2017 Accounts receivable and other long-term assets $ (5,680 ) $ 17,674 $ (2,494 ) Derivatives (638 ) 1,017 — Inventory (3,179 ) (2,127 ) (78 ) Other prepaids 583 547 2,674 Accounts payable and accrued and other long-term liabilities (1,367 ) 9,034 15,617 Prepaid tax and taxes receivable and payable (83,593 ) (47,566 ) (44,936 ) Net changes in assets and liabilities from operating activities $ (93,874 ) $ (21,421 ) $ (29,217 )
Schedule of Additional Supplemental Cash Flow Disclosures	The following table provides additional supplemental cash flow disclosures: Year Ended December 31, 2019 2018 2017 Cash paid for income taxes $ 49,196 $ 46,277 $ 54,505 Cash paid for interest $ 37,767 $ 16,038 $ 9,684 Non-cash investing activities: Net liabilities related to property, plant and equipment, end of year $ 77,353 $ 85,204 $ 76,352

Significant Accounting Polici_3

Significant Accounting Policies - Investment in PetroTal Corp (Details)	12 Months Ended
	Dec. 31, 2019director
Schedule of Equity Method Investments [Line Items]
Number of directors eligible to be nominated by the company	2
Petro Tal
Schedule of Equity Method Investments [Line Items]
Ownership interest divested (as a percent)	37.00%

Significant Accounting Polici_4

Significant Accounting Policies - Income Taxes - Intra-Entity Transfers of Assets Other than Inventory (Narrative) (Details) - USD ($) $ in Thousands	Jan. 01, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)		$ 57,285	$ 48,871	$ 69,038
Deferred tax asset			$ 22,018
Deficit | ASU 2016-16 | New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	$ 124,500
Deferred tax asset	178,600
Prepaid income taxes	$ 54,100

Significant Accounting Polici_5

Significant Accounting Policies - Goodwill (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Accounting Policies [Abstract]
Goodwill, impairment loss	$ 0

Significant Accounting Polici_6

Significant Accounting Policies - Convertible Senior Notes (Narrative) (Details) - Convertible Senior Notes - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	$ 115,000,000
5.00% Convertible Senior Notes due 2021
Debt Instrument [Line Items]
Stated interest rate	5.00%

Significant Accounting Polici_7

Significant Accounting Policies - Recently Issued Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	$ 3,800
Operating lease, liability	$ 4,200
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, weighted average discount rate, percent	5.60%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, weighted average discount rate, percent	9.10%
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for accounting changes related to leases and tax reorganizations (Note 2)	$ 400	$ (389)	$ 0	$ 124,476

Segment and Geographic Report_3

Segment and Geographic Reporting - Schedule of Information on Reportable Segments and Other Activities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	1
Segment Reporting Information [Line Items]
Depletion, depreciation and accretion (Note 5)	$ 225,033	$ 197,867	$ 131,335
Asset impairment			1,514
General and administrative expenses	34,730	39,483	39,014
Interest expense			13,882
Loss on sale	0	0	(44,385)
Income (loss) before income taxes	95,975	151,487	37,330
Segment capital expenditures	$ 379,314	$ 347,093	251,041
Oil and Gas Service
Segment Reporting Information [Line Items]
Oil and natural gas sales			421,734
Reportable Segments | Colombia
Segment Reporting Information [Line Items]
Depletion, depreciation and accretion (Note 5)			126,453
Asset impairment			0
General and administrative expenses			23,500
Interest expense			486
Loss on sale			0
Income (loss) before income taxes			111,829
Segment capital expenditures			242,636
Reportable Segments | Colombia | Oil and Gas Service
Segment Reporting Information [Line Items]
Oil and natural gas sales			413,316
Reportable Segments | All Other
Segment Reporting Information [Line Items]
Depletion, depreciation and accretion (Note 5)			4,882
Asset impairment			1,514
General and administrative expenses			15,514
Interest expense			13,396
Loss on sale			(44,385)
Income (loss) before income taxes			(74,499)
Segment capital expenditures			8,405
Reportable Segments | All Other | Oil and Gas Service
Segment Reporting Information [Line Items]
Oil and natural gas sales			$ 8,418

Accounts Receivable - Schedule

Accounts Receivable - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 36,291	$ 26,177
Trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	24,890	16,332
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable	$ 11,401	$ 9,845

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 4,187,661
Accumulated depletion and depreciation	(2,610,268)
Total Property, Plant and Equipment (Notes 5)	1,577,393
Property, plant and equipment, gross		$ 3,702,958
Accumulated depletion and depreciation		(2,390,181)
Total Property, Plant and Equipment (Notes 5)	1,577,393	1,312,777
Right-of-use asset	5,700
Oil and natural gas properties
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,161,374	3,683,409
Proved
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,850,565	3,226,811
Unproved
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	310,809	456,598
Other(1)
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 26,287
Property, plant and equipment, gross		$ 19,549

Property, Plant and Equipment_2

Property, Plant and Equipment - Narrative (Details) $ in Thousands	Feb. 20, 2019USD ($)	Dec. 01, 2018USD ($)	Aug. 06, 2018USD ($)	Jun. 20, 2018USD ($)	Dec. 31, 2019USD ($)$ / bbl	Dec. 31, 2018USD ($)$ / bbl	Dec. 31, 2017USD ($)$ / bbl	Jun. 30, 2019	Oct. 01, 2018
Property, Plant and Equipment [Line Items]
Depletion and depreciation expense					$ 220,800	$ 197,000	$ 126,800
Payments to acquire assets	$ 79,100
Consideration transferred, liabilities incurred	$ 1,500
Loss on sale of business unit					$ 0	$ 0	(44,385)
Costs not expected to be subject to depletion (as a percent)					100.00%
Period until transferred to depletable base					5 years
Peru business unit | Disposed of by sale
Property, Plant and Equipment [Line Items]
Loss on sale of business unit							34,100
Brazil business unit | Disposed of by sale
Property, Plant and Equipment [Line Items]
Loss on sale of business unit							$ 10,200
Suroriente block
Property, Plant and Equipment [Line Items]
Percentage of working interests acquired	36.20%
Llanos-5 Block
Property, Plant and Equipment [Line Items]
Percentage of working interests acquired	100.00%
Llanos-5 Block | Unproved
Property, Plant and Equipment [Line Items]
Payments to acquire oil and gas property	$ 300
PUT-1 Block In The Putumayo Basin
Property, Plant and Equipment [Line Items]
Percentage of working interests acquired									45.00%
Payments to acquire assets			$ 28,100
PUT-1 Block In The Putumayo Basin | Proved
Property, Plant and Equipment [Line Items]
Payments to acquire oil and gas property			15,200
VMM-2 Block in the Middle Magdalena Valley Basin
Property, Plant and Equipment [Line Items]
Percentage of working interests acquired		80.00%						20.00%
Payments to acquire assets		$ 5,000	17,000
VMM-2 Block in the Middle Magdalena Valley Basin | Proved
Property, Plant and Equipment [Line Items]
Payments to acquire oil and gas property		$ 1,600	$ 6,200
Alea 1848-A and 1947-C Blocks in the Putumayo Basin | Unproved
Property, Plant and Equipment [Line Items]
Payments to acquire oil and gas property				$ 3,100
Crude Oil and NGL
Property, Plant and Equipment [Line Items]
Average Brent price per barrel (in USD per barrel) | $ / bbl					64.20	72.08	54.19

Property, Plant and Equipment_3

Property, Plant and Equipment - Schedule of Asset Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Impairment of oil and gas properties	$ 0	$ 0	$ 1,514

Property, Plant and Equipment_4

Property, Plant and Equipment - Summary of Oil and Natural Gas Properties (Details) - USD ($) $ in Thousands	12 Months Ended				48 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Total oil and natural gas properties not subject to depletion	$ 81,435	$ 48,464	$ 22,909	$ 158,001	$ 310,809
Non-Segment | Ecuador
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Exploration costs	3,208	0	0	0	3,208
Colombia | Reportable Segments
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Acquisition costs	21,773	14,115	10,700	135,202	181,790
Exploration costs	$ 56,454	$ 34,349	$ 12,209	$ 22,799	$ 125,811

Property, Plant and Equipment_5

Property, Plant and Equipment - Cost of Assets Acquired (Details) $ in Thousands	Feb. 20, 2019USD ($)
Cost of asset acquisition:
Cash	$ 79,100
Promissory note	1,500
Consideration transferred	80,600
Oil and gas properties	97,298
Net working capital (including cash acquired of $5.3 million)	(16,698)
Net assets acquired	80,600
Cash acquired	5,300
Proved
Cost of asset acquisition:
Oil and gas properties	52,530
Unproved
Cost of asset acquisition:
Oil and gas properties	$ 44,768

Debt and Debt Issuance Costs -

Debt and Debt Issuance Costs - Schedule of Debt (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Feb. 15, 2018
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (21,081,000)	$ (15,585,000)
Finance Lease, Liability	3,540,000
Long-term debt	700,459,000	399,415,000
Finance lease, liability, current	$ 3,300,000
Senior Notes | 6.25% Senior Notes
Debt Instrument [Line Items]
Stated interest rate	6.25%		6.25%
Long-term debt, gross	$ 300,000,000	300,000,000	$ 300,000,000
Senior Notes | 7.75% Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	300,000,000	0
Convertible Notes
Debt Instrument [Line Items]
Long-term debt, gross	0	115,000,000
Revolving credit facility | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt, gross	$ 118,000,000	$ 0

Debt and Debt Issuance Costs _2

Debt and Debt Issuance Costs - Senior Notes (Details) - USD ($)	May 23, 2019	May 20, 2019	Feb. 15, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Proceeds from issuance of senior long-term debt				$ 289,271,000	$ 288,131,000	$ 0
Senior Notes | 7.75% Senior Notes due 2027
Debt Instrument [Line Items]
Face amount		$ 300,000,000
Stated interest rate		7.75%		7.75%
Proceeds from issuance of senior long-term debt		$ 289,300,000
Redemption price (as a percent)	100.00%
Senior Notes | 7.75% Senior Notes due 2027 | 2023
Debt Instrument [Line Items]
Redemption price (as a percent)	103.875%
Senior Notes | 7.75% Senior Notes due 2027 | 2024
Debt Instrument [Line Items]
Redemption price (as a percent)	101.938%
Senior Notes | 7.75% Senior Notes due 2027 | 2025 and Thereafter
Debt Instrument [Line Items]
Redemption price (as a percent)	100.00%
Senior Notes | 6.25% Senior Notes
Debt Instrument [Line Items]
Stated interest rate			6.25%	6.25%
Proceeds from issuance of senior long-term debt			$ 288,100,000
Redemption price (as a percent)			100.00%
Long-term debt, gross			$ 300,000,000	$ 300,000,000	$ 300,000,000
Senior Notes | 6.25% Senior Notes | 2023
Debt Instrument [Line Items]
Redemption price (as a percent)			101.563%
Senior Notes | 6.25% Senior Notes | 2022
Debt Instrument [Line Items]
Redemption price (as a percent)			103.125%
Senior Notes | 6.25% Senior Notes | 2024 and Thereafter
Debt Instrument [Line Items]
Redemption price (as a percent)			100.00%

Debt and Debt Issuance Costs _3

Debt and Debt Issuance Costs - Convertible Notes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Gain (loss) on repurchase of debt instrument	$ (11,501,000)	$ 0	$ 0
Amortization of debt issuance costs	3,376,000	3,183,000	2,415,000
Net proceeds from sale of the Notes	342,575,000	4,560,000	$ 167,043,000
Convertible Senior Notes
Debt Instrument [Line Items]
Repurchase amount	$ 114,999,000
Shares repurchased and canceled (in shares)	114,997,000
Redemption price (as a percent)	107.50%
Interest paid	$ 1,600,000
Gain (loss) on repurchase of debt instrument	(11,500,000)
Amortization of debt issuance costs	2,300,000
Long-term debt, gross	$ 0	$ 115,000,000
Convertible Senior Notes | 5.00% Convertible Senior Notes due 2021
Debt Instrument [Line Items]
Stated interest rate	5.00%

Debt and Debt Issuance Costs _4

Debt and Debt Issuance Costs - Credit Facility (Details) - Credit Agreement - Revolving Credit Facility - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Minimum
Line of Credit Facility [Line Items]
Interest rate on undrawn amounts	0.41%	0.41%
Maximum
Line of Credit Facility [Line Items]
Interest rate on undrawn amounts	0.91%	0.91%
London Interbank Offered Rate (LIBOR) | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.65%	1.65%
London Interbank Offered Rate (LIBOR) | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.65%	3.65%
Base Rate | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.65%	0.65%
Base Rate | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.65%	2.65%
Readily available
Line of Credit Facility [Line Items]
Readily available	$ 300

Debt and Debt Issuance Costs _5

Debt and Debt Issuance Costs - Schedule of Total Interest Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Contractual interest and other financing expenses	$ 39,892	$ 24,181	$ 11,467
Amortization of debt issuance costs	3,376	3,183	2,415
Interest expense	$ 43,268	$ 27,364	$ 13,882

Share Capital - Schedule of Com

Share Capital - Schedule of Common Stock (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity
Beginning Balance (in shares)	387,079,027
Options exercised (in shares)	0
Ending Balance (in shares)	366,981,556	387,079,027
Common Stock
Increase (Decrease) in Stockholders' Equity
Beginning Balance (in shares)	387,079,027	385,191,042	390,807,194
Options exercised (in shares)		549,189
Shares repurchased and canceled (in shares)	(20,097,471)	(4,772,869)	(7,704,381)
Exchange of exchangeable shares		6,111,665	2,088,229
Ending Balance (in shares)	366,981,556	387,079,027	385,191,042
Common Stock | Exchangeable Shares of Gran Tierra Exchangeco Inc.
Increase (Decrease) in Stockholders' Equity
Beginning Balance (in shares)	0	4,422,776	4,812,592
Options exercised (in shares)		0
Shares repurchased and canceled (in shares)	0	0	0
Exchange of exchangeable shares		(4,422,776)	(389,816)
Ending Balance (in shares)	0	0	4,422,776
Common Stock | Exchangeable Shares of Gran Tierra Goldstrike Inc.
Increase (Decrease) in Stockholders' Equity
Beginning Balance (in shares)	0	1,688,889	3,387,302
Options exercised (in shares)		0
Shares repurchased and canceled (in shares)	0		0
Exchange of exchangeable shares		(1,688,889)	(1,698,413)
Ending Balance (in shares)	0	0	1,688,889

Share Capital - Additional Info

Share Capital - Additional Information (Details)	Jul. 09, 2018shares	Jul. 05, 2018shares	Dec. 31, 2019vote$ / sharesshares	Dec. 31, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized share capital (in shares)			595,000,000
Common stock, shares authorized (in shares)			570,000,000
Common shares, par value (in USD per share) | $ / shares			$ 0.001	$ 0.001
Preferred Stock, shares authorized (in shares)			25,000,000
Preferred Stock, par value (in USD per share) | $ / shares			$ 0.001
Subsidiary redemption, shares issues to redeem outstanding shares		1
Number of votes per common stock | vote			1
Special A Voting Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, canceled	1
Special B Voting Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, canceled	1

Share Capital - Share Repurchas

Share Capital - Share Repurchase Program (Details) - Common Stock	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Equity, Class of Treasury Stock [Line Items]
Stock repurchased program, weighted average price (in dollars per shares) | $ / shares	$ 1.87
Share repurchased during period (in shares) | shares	20,097,471
2019 Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares authorized to be repurchased (in shares) | shares	19,353,951
Stock repurchase program, number of shares authorized to be repurchased, percent of issued and outstanding shares of common stock (percent)	5.00%
Stock repurchased program, weighted average price (in dollars per shares) | $ / shares	$ 1.85
2018 Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchased program, weighted average price (in dollars per shares) | $ / shares	$ 2.34
Share repurchased during period (in shares) | shares	743,520

Share Capital - Equity Compensa

Share Capital - Equity Compensation Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 27, 2012	Jun. 26, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance (in shares)				39,806,100	23,306,100
Share-based compensation	$ 1,430	$ 8,299	$ 9,775
Unrecognized compensation cost	$ 6,700	9,200
Weighted average period of recognition	1 year 8 months 12 days
Weighted average remaining contractual term	2 years 3 months 18 days
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards granted (as a percent)	80.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity awards granted (as a percent)	20.00%
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 1,400	$ 8,300	$ 9,800

Share Capital - Schedule of Inf

Share Capital - Schedule of Information About PSU, DSU, RSU and Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Number of Outstanding Stock Options
Balance, Beginning of period (in shares)	9,034,412
Granted (in shares)	2,943,990
Exercised (in shares)	0
Forfeited (in shares)	(1,213,170)
Expired (in shares)	(152,360)
Balance, End of period (in shares)	10,612,872
Exercisable, at end of period (in shares)	6,469,699
Vested, or expected to vest, at end of period through the life of the options (in shares)	10,445,530
Weighted Average Exercise Price /Stock Option ($)
Balance, Beginning of period (in USD per share) | $ / shares	$ 3.18
Granted (in USD per share) | $ / shares	2.04
Exercised (in USD per share) | $ / shares	0
Forfeited (in USD per share) | $ / shares	3.61
Expired (in USD per share) | $ / shares	5.27
Balance, End of period (in USD per share) | $ / shares	2.78
Exercisable, at end of period (in USD per share) | $ / shares	3.14
Vested, or expected to vest, at end of period through the life of the options (in USD per share) | $ / shares	$ 2.79
PSUs
Number of Outstanding Share Units
Balance, Beginning of period (in shares)	9,004,661
Granted (in shares)	6,355,214
Exercised (in shares)	(2,725,877)
Forfeited (in shares)	(1,262,631)
Expired (in shares)	0
Balance, End of period (in shares)	11,371,367
DSUs
Number of Outstanding Share Units
Balance, Beginning of period (in shares)	684,893
Granted (in shares)	567,101
Exercised (in shares)	0
Forfeited (in shares)	0
Expired (in shares)	0
Balance, End of period (in shares)	1,251,994

Share Capital - PSUs (Narrative

Share Capital - PSUs (Narrative) (Details) - PSUs - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Vested and will be settled in cash (in shares)	2,400,000	2,700,000
Award subject to targets relating to total shareholder return (as a percent)	50.00%
Award subject to targets relating to net asset value (as a percent)	25.00%
Net present value discount rate	10.00%
Award subject to targets relating to execution of corporate strategy (as a percent)	25.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of PSUs that vest (as a percent)	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of PSUs that vest (as a percent)	200.00%

Share Capital - DSUs and RSUs (

Share Capital - DSUs and RSUs (Narrative) (Details) - DSUs - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
DSUs that will vest at such time the grantee ceases to be a member (as a percent)	100.00%
Outstanding award (in shares)	1,251,994	684,893

Share Capital - Stock Options (

Share Capital - Stock Options (Narrative) (Details) - USD ($)	Apr. 30, 2013	May 31, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation award, common stock for purchase, exercise price			1
Stock issued, exercise of stock options (in shares)			0	549,189	0
Proceeds from exercise of stock options			$ 0	$ 1,429,000	$ 0
Share-based compensation arrangement by share-based payment award, options, vested and expected to vest, outstanding, weighted average remaining contractual term			2 years 3 months 18 days
Weighted average remaining contractual term of exercisable stock options			1 year 3 months 18 days
Weighted average grant date fair value for options granted (in USD per share)			$ 0.89	$ 1.15	$ 1.11
Weighted average grant date fair value for options vested (in USD per share)			$ 1.10	$ 1.23	$ 1.31
Total fair value of stock options vested			$ 1,900,000	$ 2,800,000	$ 2,500,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Expected term during grantee's service		5 years
Expected term after end of grantee's service		3 months
Term for stock options granted prior to May of 2013	10 years

Share Capital - Schedule of Ass

Share Capital - Schedule of Assumptions Using the Black-Scholes Option Pricing Model (Details) - Stock Options	1 Months Ended	12 Months Ended
	May 31, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield (per share) (as a percent)		0.00%	0.00%	0.00%
Volatility (minimum) (as a percent)		48.00%	51.00%	51.00%
Volatility (maximum) (as a percent)		54.00%	55.00%	53.00%
Weighted average volatility (as a percent)		51.00%	54.00%	52.00%
Risk-free interest rate (minimum) (as a percent)		1.49%	2.18%	1.75%
Risk-free interest rate (maximum) (as a percent)		2.54%	3.00%	2.10%
Expected term	5 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term		4 years	4 years	4 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term		5 years	5 years	5 years

Share Capital - Schedule Of Wei

Share Capital - Schedule Of Weighted Average Shares Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Weighted average number of common and exchangeable shares outstanding (in shares)	376,495,306	390,930,453	396,683,593
Shares issuable pursuant to stock options (in shares)	87,204	4,207,542	0
Shares assumed to be purchased from proceeds of stock options (in shares)	(74,698)	(3,832,516)	0
Shares issuable on conversion of Convertible Notes (in shares)	0	35,814,393	0
Weighted average number of diluted common and exchangeable shares outstanding (in shares)	376,507,812	427,119,872	396,683,593

Share Capital - Weighted Averag

Share Capital - Weighted Average Shares Outstanding (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average options excluded from diluted loss per share calculation (in shares)	9,465,737	5,354,545	9,681,304

Asset Retirement Obligation - S

Asset Retirement Obligation - Schedule of Changes in Carrying Amount of Asset Retirement Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis
Balance, beginning of year	$ 43,799	$ 31,564
Liability incurred	7,034	6,985
Settlements	(846)	(600)
Accretion	3,436	2,772
Revisions in estimated liability	(10,004)	2,351
Liabilities assumed in acquisitions	0	727
Balance, end of year	43,419	43,799
Asset retirement obligation - current			$ 0	$ 123
Asset retirement obligation - long-term			43,419	43,676
Balance, end of year	$ 43,799	$ 43,799	$ 43,419	$ 43,799

Asset Retirement Obligation - N

Asset Retirement Obligation - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Fair value of assets legally restricted for purposes of settling asset retirement obligations	$ 2.8	$ 2.7

Revenue (Details)

Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Revenue, information used to assess variable consideration constraint, adjustment for quality and transportation	16.00%	18.00%	21.00%
Contract with customer, asset, net, current	$ 0.1	$ 4.2
Revenue from Contract with Customer | Product Concentration Risk
Concentration Risk [Line Items]
Sales to each significant customer as % of oil and gas sales	100.00%	100.00%	99.00%

Taxes - Schedule of Income Tax

Taxes - Schedule of Income Tax Expense Reported (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
United States	$ (27,984)	$ (14,610)	$ (51,215)
Foreign	123,959	166,097	88,545
INCOME BEFORE INCOME TAXES	$ 95,975	$ 151,487	$ 37,330
Statutory rate	33.00%	37.00%	35.00%
Income tax expense expected	$ 31,672	$ 56,050	$ 13,066
Impact of foreign taxes	9,387	7,011	12,310
Foreign currency translation	11,527	10,336	(118)
Other local taxes	504	524	1,056
Stock-based compensation	430	324	2,001
Change in valuation allowance	3,429	(21,954)	52,269
Non-deductible third party royalty in Colombia	2,240	3,194	3,194
Other permanent differences	(1,904)	(6,614)	(14,740)
INCOME TAX EXPENSE (RECOVERY)	$ 57,285	$ 48,871	$ 69,038
Effective tax rate	60.00%	32.00%	185.00%
Current income tax expense
United States	$ 0	$ 0	$ 3,457
Foreign	17,058	43,903	20,865
Current income tax expense	17,058	43,903	24,322
Deferred income tax expense
Foreign	$ 40,227	$ 4,968	$ 44,716

Taxes - Schedule of Deferred Ta

Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax benefit of operating loss carryforwards	$ 73,096	$ 51,042
Tax basis in excess of book basis	544	8,854
Foreign tax credits and other accruals	76,720	79,820
Tax benefit of capital loss carryforwards	22,710	32,737
Deferred tax assets before valuation allowance	173,070	172,453
Valuation allowance	(129,067)	(127,016)
Deferred tax assets, net	44,003	45,437
Deferred tax liabilities	59,762	23,419
Net deferred tax (liabilities) assets	$ 15,759
Net deferred tax (liabilities) assets		$ 22,018

Taxes - Summary of Operating Lo

Taxes - Summary of Operating Loss and Capital Loss Carryforwards (Details) - USD ($)	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Operating loss carryforwards		$ 159,200,000
Unrecognized tax benefits	$ 0	0
Impairment of taxes receivable	(1,400,000)
Colombia
Tax Credit Carryforward [Line Items]
Credit carryforward		3,300,000
Internal Revenue Service (IRS)
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	50,500,000	22,700,000
Canada Revenue Agency
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	31,500,000	27,100,000
Canada Revenue Agency | Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Credit carryforward	197,500,000	242,400,000
Colombian Tax and Customs National Authority
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	140,500,000	99,000,000
Operating loss carryforwards, not subject to limitations			$ 75,400,000
Operating loss carryforwards, subject to limitations			$ 83,800,000
Colombian Tax and Customs National Authority | Capital Loss Carryforward
Tax Credit Carryforward [Line Items]
Credit carryforward	$ 1,500,000	$ 2,200,000

Accounts Payable and Accrued _3

Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Trade	$ 151,747	$ 123,905
Royalties	5,758	3,550
Employee compensation	6,861	8,195
Other	31,147	19,020
Total	$ 195,513	$ 154,670

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Payments Under Non-Cancelable Agreements (Details) $ in Thousands	Dec. 31, 2019USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	$ 36,531
2020	16,281
2021	12,466
2022	7,450
2023	103
2024	104
Thereafter	127
Operating leases
Total	5,679
2020	2,708
2021	1,694
2022	1,277
2023	0
2024	0
Thereafter	0
Finance leases
Total	6,232
2020	2,760
2021	3,192
2022	84
2023	84
2024	84
Thereafter	28
Oil transportation services
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	3,211
2020	3,211
2021	0
2022	0
2023	0
2024	0
Thereafter	0
Drilling, completions and seismic
Unrecorded Unconditional Purchase Obligation [Line Items]
Total	21,409
2020	7,602
2021	7,580
2022	6,089
2023	19
2024	20
Thereafter	$ 99

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Promissory notes as security for letters of credit	$ 120.6	$ 76.7

Financial Instruments, Fair V_3

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017	Dec. 31, 2019$ / shares	May 20, 2019	Dec. 31, 2018$ / shares	Feb. 15, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment - current and long-term assets	$ 94,741	$ 41,435
Foreign exchange losses for each one peso decrease in exchange rate of Colombian peso to one U.S. dollar	$ (6)
Colombia
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revenues received in U.S. dollars (as a percent)	100.00%
Colombia | Geographic Concentration Risk | Oil and natural gas sales
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Sales to each significant customer as % of oil and gas sales	100.00%	100.00%	98.00%
6.25% Senior Notes | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	6.25%						6.25%
7.75% Senior Notes due 2027 | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	7.75%				7.75%
Reported Value Measurement | 6.25% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 290,700
Reported Value Measurement | 7.75% Senior Notes due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	289,900
Estimate of Fair Value Measurement | 6.25% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	272,800
Estimate of Fair Value Measurement | 7.75% Senior Notes due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	279,100
PetroTal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment - current and long-term assets	$ 94,700
Closing share price (in dollars per share) | (per share)	$ 0.38	$ 0.17		$ 0.50		$ 0.24

Financial Instruments, Fair V_4

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Schedule of Fair Value of Trading Securities, Derivative Assets, and RSU and PSU Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Investment - current and long-term assets	$ 94,741	$ 41,435
Fair value of assets	94,741	41,435
Derivative liability	775	1,017
PSU and DSU liability	7,859	17,683
Fair value of liabilities	$ 8,634	$ 18,700

Financial Instruments, Fair V_5

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Schedule of Losses or Gains on Financial Instruments Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment gain	$ (49,884)	$ (786)	$ (111)
Financial instruments loss	(46,215)	12,296	15,929
Commodity price derivative loss
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative loss (gain)	3,642	13,972	17,327
Foreign currency derivative loss (gain)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative loss (gain)	$ 27	$ (890)	$ (1,287)

Financial Instruments, Fair V_6

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Rollforward of Level 3 Financial Asset (Details) - Equity Securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Opening balance	$ 8,711	$ 19,147
Transfer from long-term (Level 3) to current (Level 1)	(11,881)	(10,522)
Unrealized gain on valuation	2,604	846
Unrealized gain (loss) on foreign exchange	566	(760)
Closing balance	$ 0	$ 8,711

Financial Instruments, Fair V_7

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Commodity Price Risk (Details) - Forecast - Commodity Hedge - Collars: January 1, to June 30, 2020	6 Months Ended
	Jun. 30, 2020$ / bbl$ / collarbbl
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl	6,000
Purchased | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel) | $ / bbl	55
Sold | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Cap Price | $ / collar	69.05

Financial Instruments, Fair V_8

Financial Instruments, Fair Value Measurement, Credit Risk and Foreign Exchange Risk - Foreign Exchange Risk (Details) - Forecast - Collars: January 1, to December 31, 2020 $ in Thousands, $ in Millions	Dec. 31, 2020USD ($)$ / collar	Dec. 31, 2020COP ($)$ / collar
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount hedged	$ 40,994	$ 134,500
Sold | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor Price (COP, Weighted Average)	3,305	3,305
Purchased | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cap Price (COP, Weighted Average)	3,423	3,423

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Reconciliation of Cash, Cash Equivalents, and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 8,301	$ 51,040	$ 12,326
Restricted cash and cash equivalents - current	516	1,269	11,787
Restricted cash and cash equivalents - long-term	2,258	1,999	2,565
Cash, cash equivalents, restricted cash, and restricted cash equivalents	$ 11,075	$ 54,308	$ 26,678	$ 43,267

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information - Schedule of Net Changes in Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Accounts receivable and other long-term assets	$ (5,680)	$ 17,674	$ (2,494)
Derivatives	(638)	1,017	0
Inventory	(3,179)	(2,127)	(78)
Other prepaids	583	547	2,674
Accounts payable and accrued and other long-term liabilities	(1,367)	9,034	15,617
Prepaid tax and taxes receivable and payable	(83,593)	(47,566)	(44,936)
Net changes in assets and liabilities from operating activities	$ (93,874)	$ (21,421)	$ (29,217)

Supplemental Cash Flow Inform_5

Supplemental Cash Flow Information - Schedule of Additional Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash paid for income taxes	$ 49,196	$ 46,277	$ 54,505
Cash paid for interest	37,767	16,038	9,684
Non-cash investing activities:
Net liabilities related to property, plant and equipment, end of year	$ 77,353	$ 85,204	$ 76,352